Modelling the COVID-19 Pandemic: Asymptomatic Patients, Lockdown and Herd Immunity

The SARS-Cov-2 is a type of coronavirus that has caused the COVID-19 pandemic. In traditional epidemiological models such as SEIR (Susceptible, Exposed, Infected, Removed), the exposed group E does not infect the susceptible group S. A distinguishing feature of COVID-19 is that, unlike with previous viruses, there is a distinct "asymptomatic" group A, who do not show any symptoms, but can nevertheless infect others, at the same rate as infected patients. This situation is captured in a model known as SAIR (Susceptible, Asymptomatic, Infected, Removed), introduced in Robinson and Stilianakis (2013). The dynamical behavior of the SAIR model is quite different from that of the SEIR model. In this paper, we use Lyapunov theory to establish the global asymptotic stabiilty of the SAIR model. Next, we present methods for estimating the parameters in the SAIR model. We apply these estimation methods to data from several countries including India, and show that the predicted trajectories of the disease closely match actual data.

Modeling the impact of racial and ethnic disparities on COVID-19 epidemic dynamics

Background

The impact of variable infection risk by race and ethnicity on the dynamics of SARS-CoV-2 spread is largely unknown.

Methods

Here, we fit structured compartmental models to seroprevalence data from New York State and analyze how herd immunity thresholds (HITs), final sizes, and epidemic risk change across groups.

Results

A simple model where interactions occur proportionally to contact rates reduced the HIT, but more realistic models of preferential mixing within groups increased the threshold toward the value observed in homogeneous populations. Across all models, the burden of infection fell disproportionately on minority populations: in a model fit to Long Island serosurvey and census data, 81% of Hispanics or Latinos were infected when the HIT was reached compared to 34% of non-Hispanic whites.

Conclusions

Our findings, which are meant to be illustrative and not best estimates, demonstrate how racial and ethnic disparities can impact epidemic trajectories and result in unequal distributions of SARS-CoV-2 infection.

Funding

K.C.M. was supported by National Science Foundation GRFP grant DGE1745303. Y.H.G. and M.L. were funded by the Morris-Singer Foundation. M.L. was supported by SeroNet cooperative agreement U01 CA261277.

The assembly effect: the connectedness between populations is a double-edged sword for public health interventions

Background

Many public health interventions lead to disruption or decrease of transmission, providing a beneficial effect for people in the population regardless of whether or not they individually participate in the intervention. This protective benefit has been referred to as a herd or community effect and is dependent on sufficient population participation. In practice, public health interventions are implemented at different spatial scales (i.e., at the village, district, or provincial level). Populations, however defined (i.e., neighbourhoods, villages, districts) are frequently connected to other populations through human movement or travel, and this connectedness can influence potential herd effects.

Methods

The impact of a public health intervention (mass drug administration for malaria) was modelled, for different levels of connectedness between populations that have similar disease epidemiology (e.g., two nearby villages which have similar baseline malaria incidences and similar malaria intervention measures), or between populations of varying disease epidemiology (e.g., two nearby villages which have different baseline malaria incidences and/or malaria intervention measures).

Results

The overall impact of the interventions deployed could be influenced either positively (adding value to the intervention) or negatively (reducing the impact of the intervention) by how much the intervention units are connected with each other (e.g., how frequent people go to the other village or town) and how different the disease intensity between them are. This phenomenon is termed the “assembly effect”, and it is a meta-population version of the more commonly understood “herd effect”.

Conclusions

The connectedness of intervention units or populations is an important factor to be considered to achieve success in public health interventions that could provide herd effects. Appreciating the assembly effect can improve the cost-effective strategies for global disease elimination projects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03726-x.

The impact of childhood pneumococcal conjugate vaccine immunisation on all-cause pneumonia admissions in Hong Kong: A 14-year population-based interrupted time series analysis

BACKGROUND

Nine years after the introduction of pneumococcal conjugate vaccine (PCV) in the United States, Hong Kong (HK) introduced the vaccine to its universal childhood immunisation programme in 2009. We aimed to assess the impact of childhood PCV immunisation on all-cause pneumonia (ACP) admissions among the overall population of HK.

METHODS

In this population-based interrupted time series analysis, we used territory-wide population-representative electronic health records in HK to evaluate the vaccine impact. We identified hospitalised patients with a diagnosis of pneumonia from any cause between 2004 and 2017. We applied segmented Poisson regression to assess the gradual change in the monthly incidence of ACP admissions between pre- and post-vaccination periods. Negative outcome control, subgroup and sensitivity analyses were used to test the robustness of the main analysis.

FINDINGS

Over the 14-year study period, a total of 587,607 ACP episodes were identified among 357,950 patients. The monthly age-standardised incidence of ACP fluctuated between 33.42 and 87.44 per 100,000-persons. There was a marginal decreasing trend in pneumonia admissions after PCV introduction among overall population (incidence rate ratio [IRR]: 0·9965, 95% confidence interval [CI]: 0·9932-0·9998), and older adults (≥65 years, IRR: 0·9928, 95% CI: 0·9904-0·9953) but not in younger age groups.

INTERPRETATION

There was a marginally declining trend of overall ACP admissions in HK up to eight years after childhood PCV introduction. The significance disappeared when fitting sensitivity analyses. The results indicate the complexities of using non-specific endpoints for measuring vaccine effect and the necessity of enhancing serotype surveillance systems for replacement monitoring.

FUNDING

Health and Medical Research Fund, Food and Health Bureau of the Government of Hong Kong (Reference number: 18171272).

The New Totalitarians: The Swedish COVID-19 strategy and the implications of consensus culture and media policy for public health

Aims

The aim is to discuss implications of consensus culture in combination with media policy in Sweden with regard to the Swedish COVID-19 strategy in the spring of 2020.

Methods

Investigation of prerequisites for scrutiny by the Swedish mass media of the Swedish strategy in the spring of 2020 based on discussion regarding consensus culture, media structure and postmodernism in science, politics and administration.

Results

The Swedish strategy entailed strong initial confidence in herd immunity (although not officially stated), individual responsibility, evidence based medicine and substantial neglect to cooperate internationally. The strategy may be regarded partly as a result of the postmodern view of science and society predominant in Sweden. A tradition of top down consensus culture combined with mass media's financial and partly structural dependence of the state may help explain the comparative lack of critical questions regarding the strategy at the press conferences in the spring of 2020.

Conclusions

Mass media in Sweden should become more financially and structurally independent of the state. The reporting by Swedish media in the spring of 2020 should be subject to peer-reviewed research.

From "Coffin Dodger" to "Boomer Remover": Outbreaks of Ageism in Three Countries With Divergent Approaches to Coronavirus Control

OBJECTIVES

This article compares responses to coronavirus control in Australia, the United Kingdom, and the United States, 3 countries in which public ageism erupted over the social and economic costs of protecting older adults from Covid-19.

METHODS

Thirty-five (35) newspapers, media websites, and current affairs magazines were sourced for the study: 8 for Australia, 12 for the United Kingdom, and 15 for the United States. Searches were conducted daily from April to June 2020, using key words to identify age-related themes on pandemic control.

RESULTS

Despite divergent policies in the 3 countries, ageism took similar forms. Public responses to lockdowns and other measures cast older adults as a problem to be ignored or solved through segregation. Name-calling, blame, and "so-be-it" reactions toward age vulnerability were commonplace. Policies banning visits to aged care homes angered many relatives and older adults. Indefinite isolation for older adults was widely accepted, especially as a vehicle to end public lockdowns and economic crises.

DISCUSSION

Older adults have and will continue to bear the brunt of Covid-19 in terms of social burdens and body counts as the pandemic continues to affect people around the globe. The rhetoric of disposability underscores age discrimination on a broader scale, with blame toward an age cohort considered to have lived past its usefulness for society and to have enriched itself at the expense of future generations.

COVID-19: Is herd immunity the only option for fragile Yemen?

The first case of COVID-19 in Yemen was confirmed on 10 April 2020. Having faced with a six-year long conflict that has destroyed half of its healthcare facilities and displaced millions, predictions of infections and mortality in Yemen suggested a looming healthcare catastrophe. Difficulty in implementing coordinated lockdowns and preventive measures due to the daily labor working nature of the majority of the population, provided the perfect breeding ground for the SARS-CoV-2 virus. However, official figures of infections and mortality are very low and there have not been confirmed reports of excess mortality. This could indicate that Yemen is silently marching towards forced herd immunity. Seroprevalence studies will provide useful insight into the COVID-19 transmission trajectory in Yemen, which can serve as a guide in planning vaccine distribution strategies and allocating the limited funds wisely.

The burden of influenza in older adults: meeting the challenge

Influenza is an acute respiratory infection for which vaccination is our best prevention strategy. Small seasonal changes in circulating influenza viruses (antigenic drift) result in the need for annual influenza vaccination, in which the vaccine formulation is updated to better match the predominant circulating influenza viruses that have undergone important antigenic changes. Although the burden of influenza infection and its complications is the highest in older adults, vaccine effectiveness is the lowest in this vulnerable population. This is largely due to waning of the immune response with age known as "immune senescence", and presents an important, unmet challenge. Possible strategies to tackle this include adjuvant and high-dose vaccines, and herd immunity induced by greater vaccine uptake.

How best can finite-time social distancing reduce epidemic final size?

Given maximal social distancing duration and intensity, how can one minimize the epidemic final size, or equivalently the total number of individuals infected during the outbreak? A complete answer to this question is provided and demonstrated here for the SIR epidemic model. In this simplified setting, the optimal solution consists in enforcing the highest confinement level during the longest allowed period, beginning at a time instant that is the unique solution to certain 1D optimization problem. Based on this result, we present numerical essays showing the best possible performance for a large set of basic reproduction numbers and lockdown durations and intensities.

COVID-19 herd immunity in the absence of a vaccine: an irresponsible approach

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread rapidly throughout the human population, the concept of “herd immunity” has attracted the attention of both decision-makers and the general public. In the absence of a vaccine, this entails that a large proportion of the population will be infected to develop immunity that would limit the severity and/or extent of subsequent outbreaks. We argue that adopting such an approach should be avoided for several reasons. There are significant uncertainties about whether achieving herd immunity is possible. If possible, achieving herd immunity would impose a large burden on society. There are gaps in protection, making it difficult to shield the vulnerable. It would defeat the purpose of avoiding harm caused by the virus. Lastly, dozens of countries are showing that containment is possible.

Role of ACE2 receptor and the landscape of treatment options from convalescent plasma therapy to the drug repurposing in COVID-19

Since the first case reports in Wuhan, China, the SARS-CoV-2 has caused a pandemic and took lives of > 8,35,000 people globally. This single-stranded RNA virus uses Angiotensin-converting enzyme 2 (ACE2) as a receptor for entry into the host cell. Overexpression of ACE2 is mainly observed in hypertensive, diabetic and heart patients that make them prone to SARS-CoV-2 infection. Mitigations strategies were opted globally by the governments to minimize transmission of SARS-CoV-2 via the implementation of social distancing norms, wearing the facemasks, and spreading awareness using digital platforms. The lack of an approved drug treatment regimen, and non-availability of a vaccine, collectively posed a challenge for mankind to fight against the SARS-CoV-2 pandemic. In this scenario, repurposing of existing drugs and old treatment options like convalescent plasma therapy can be one of the potential alternatives to treat the disease. The drug repurposing provides a selection of drugs based on the scientific rationale and with a shorter cycle of clinical trials, while plasma isolated from COVID-19 recovered patients can be a good source of neutralizing antibody to provide passive immunity. In this review, we provide in-depth analysis on these two approaches currently opted all around the world to treat COVID-19 patients. For this, we used "Boolean Operators" such as AND, OR & NOT to search relevant research articles/reviews from the PUBMED for the repurposed drugs and the convalescent plasma in the COVID-19 treatment. The repurposed drugs like Chloroquine and Hydroxychloroquine, Tenofovir, Remdesivir, Ribavirin, Darunavir, Oseltamivir, Arbidol (Umifenovir), Favipiravir, Anakinra, and Baricitinib are already being used in clinical trials to treat the COVID-19 patients. These drugs have been approved for a different indication and belong to a diverse category such as anti-malarial/anti-parasitic, anti-retroviral/anti-viral, anti-cancer, or against rheumatoid arthritis. Although, the vaccine would be an ideal option for providing active immunity against the SARS-CoV-2, but considering the current situation, drug repurposing and convalescent plasma therapy and repurposed drugs are the most viable option against SARS-CoV-2.

COVID-19 pandemic management and the rheumatology patient

We discuss the evidence behind mask use, including evidence for homemade masks, social distancing, and the local coronavirus disease-2019 (COVID-19) epidemics in countries that initially employed more limited public health interventions. Given the absence of data for specific interventions in the rheumatic disease population, we reviewed the evidence available for the general population. The risk of poor outcomes with COVID-19 in patients with rheumatic diseases is a potential concern given the immunosuppression associated with these conditions and disease-modifying anti-rheumatic drug therapy, as well as advancing age and many of the comorbidities present in such patients. Infection prevention is key, for both individual patients and their community. Given the data collected from the general population, we recommend ongoing proper mask use, social distancing, and hand hygiene for patients with rheumatic diseases and encourage providers to counsel these patients in prevention strategies and attempt to dispel abundant misinformation.

Direct and indirect effect of 10 valent pneumococcal vaccine on nasopharyngeal carriage in children under 2 years of age in Matiari, Pakistan

Background

Pakistan introduced Ten-valent pneumococcal-conjugate-vaccine PCV10 in 2012 as a 3 + 0 schedule without catch-up.

Methods

Children <2 years old in Matiari, Sindh provided nasopharyngeal swabs between 2014 and 2018, which were cultured for pneumococcus and serotyped through multiplex PCR at the Aga Khan University Hospital. Carriage rates over time for Vaccine-Type (VT) and Non-VT (NVT) serotypes were used to estimate direct, indirect, total and overall effects of vaccination. Regression analysis was used to determine factors associated with VT carriage.

Results

Pneumococcus was detected in 2370/3140 (75%). VT carriage decreased overall, 16.1–9.6% (p-trend <0.001); vaccinated (all 3 doses of PCV10 received) 11.3–8.1% (p-trend 0.031) and unvaccinated (no PCV10 dose received) 17.4–10.3% (p-trend 0.003) with a decline in serotypes 6B, 9V/9A and 19F. Immunization increased from 41.0% to 68.4% (p-trend 0.001). Direct effect of vaccine was 32.8% (95% CI 14.7–47.0%) and indirect effect 44.6%(95% CI 40.6–48.6%). Factors associated with decreased VT colonization were education 1–5 years (aOR 0.7, 95%CI 0.6–1.0), history of difficulty breathing (aOR 0.7, 95%CI 0.5–1.0), exposure to smoke (aOR 0.8, 95% CI 0.6–1.0), child fully immunized (aOR 0.7, 95%CI 0.5–1.0) and enrolled in 3rd (aOR 0.6, 95%CI 0.4–0.8) and 4th (aOR 0.6, 95%CI 0.5–0.9) year of the study whereas history of runny nose (aOR 1.5, 95% CI 1.2–1.9) was positively associated.

Conclusions

Decrease in VT pneumococcal carriage in vaccinated and unvaccinated children indicates herd immunity. Sustained increase in vaccine coverage and close long-term surveillance is warranted.

The impact of human vaccines on bacterial antimicrobial resistance. A review

At present, the dramatic rise in antimicrobial resistance (AMR) among important human bacterial pathogens is reaching a state of global crisis threatening a return to the pre-antibiotic era. AMR, already a significant burden on public health and economies, is anticipated to grow even more severe in the coming decades. Several licensed vaccines, targeting both bacterial (Haemophilus influenzae type b, Streptococcus pneumoniae, Salmonella enterica serovar Typhi) and viral (influenza virus, rotavirus) human pathogens, have already proven their anti-AMR benefits by reducing unwarranted antibiotic consumption and antibiotic-resistant bacterial strains and by promoting herd immunity. A number of new investigational vaccines, with a potential to reduce the spread of multidrug-resistant bacterial pathogens, are also in various stages of clinical development. Nevertheless, vaccines as a tool to combat AMR remain underappreciated and unfortunately underutilized. Global mobilization of public health and industry resources is key to maximizing the use of licensed vaccines, and the development of new prophylactic vaccines could have a profound impact on reducing AMR.

The fastest national COVID vaccination in Europe - Malta's strategies

BACKGROUND

COVID-19 vaccines reduce morbidity and mortality, but mass vaccination faces multiple challenges leading to different vaccination rates in different countries. Malta, a small European country, has achieved a very rapid vaccination rollout. This paper presents a narrative review of Malta's vaccination strategy and its impact on the country's COVID-19 situation.

METHODS

Data was obtained through a literature review of Maltese newspapers and from Malta's COVID-19 government dashboard. A comprehensive summary of vaccination operations was provided by Malta's COVID-19 vaccination team.

RESULTS

Malta comprised part of the European Commission joint procurement and obtained the maximum vaccines that were eligible from all manufacturers. Four tier priority population groups were set up, with both vaccine doses (where applicable) allocated and stored for each individual. Multiple hubs were set up to simultaneously administer first and eventually second doses accordingly. To date (August 9, 2021) 398,128 of the population are fully vaccinated and 405,073 received the first dose, with both morbidity and mortality declining progressively as vaccination coverage progressed.

CONCLUSION

Malta has successfully implemented a COVID-19 strategy that rapidly covered a substantial proportion of the population over a short period of time, with herd immunity reached by end of May 2021. Low population vaccination hesitancy and high vaccine doses availability were two major factors in this success.

Optimal Immunity Control and Final Size Minimization by Social Distancing for the SIR Epidemic Model

The aim of this article is to understand how to apply partial or total containment to SIR epidemic model during a given finite time interval in order to minimize the epidemic final size, that is the cumulative number of cases infected during the complete course of an epidemic. The existence and uniqueness of an optimal strategy are proved for this infinite-horizon problem, and a full characterization of the solution is provided. The best policy consists in applying the maximal allowed social distancing effort until the end of the interval, starting at a date that is not always the closest date and may be found by a simple algorithm. Both theoretical results and numerical simulations demonstrate that it leads to a significant decrease in the epidemic final size. We show that in any case the optimal intervention has to begin before the number of susceptible cases has crossed the herd immunity level, and that its limit is always smaller than this threshold. This problem is also shown to be equivalent to the minimum containment time necessary to stop at a given distance after this threshold value.

COVID-19 zugzwang: Potential public health moves towards population (herd) immunity

COVID-19 is pandemic, and likely to become endemic, possibly returning with greater virulence. Outlining potential public health actions, including hygiene measures, social distancing and face masks, and realistic future advances, this paper focuses on the consequences of taking no public health action; the role of natural changes such as weather; the adverse public health consequences of lockdowns; testing for surveillance and research purposes; testing to identify cases and contacts, including the role of antibody tests; the public health value of treatments; mobilising people who have recovered; population (a synonym for herd) immunity through vaccination and through natural infection; involving the entire population; and the need for public debate. Until there is a vaccine, population immunity is going to occur only from infection. Allowing infection in those at very low risk while making it safer for them and wider society needs consideration but is currently taboo. About 40–50% population immunity is sufficient to suppress an infection with a reproduction number of about 1 or slightly more. Importantly, in children and young people COVID-19 is currently rarely fatal, roughly comparable with influenza. The balance between the damage caused by COVID-19 and that caused by lockdowns needs quantifying. Public debate, including on population immunity, informed by epidemiological data, is now urgent.

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The long-term solution to the COVID-19 pandemic is population immunity through natural infection or vaccination.

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40-50% population immunity is sufficient to suppress and eliminate this pandemic.

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New vaccines may not work well in the older age groups and those with underlying conditions and may not be safer than the infection for children and youth.

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Immunity is currently being acquired by infection and we need safer strategies for managing this.

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Open, honest, factual and sensitively conducted public dialogue is now urgent.

Optimal voluntary and mandatory insect repellent usage and emigration strategies to control the chikungunya outbreak on Reunion Island

In 2005, a chikungunya virus outbreak devastated the tropical island of Reunion, infecting a third of the total population. Motivated by the Reunion Island case study, we investigate the theoretic potential for two intervention measures under both voluntary and mandatory protocols to control a vector-borne disease when there is risk of the disease becoming endemic. The first measure uses insect repellent to prevent mosquito bites, while the second involves emigrating to the neighboring Mauritius Island to avoid infection. There is a threshold on the cost of using repellent above which both voluntary and mandatory regimes find it optimal to forgo usage. Below that threshold, mandatory usage protocols will eradicate the disease; however, voluntary adoption leaves the disease at a small endemic level. Emigrating from the island to avoid infection results in a tragedy-of-the-commons effect: while being potentially beneficial to specific susceptible individuals, the remaining islanders paradoxically face a higher risk of infection. Mandated relocation of susceptible individuals away from the epidemic is viable only if the cost of this relocation is several magnitudes lower than the cost of infection. Since this assumption is unlikely to hold for chikungunya, it is optimal to discourage such emigration for the benefit of the entire population. An underlying assumption about the conservation of human-vector encounter rates in mosquito biting behavior informs our conclusions and may warrant additional experimental verification.

Heterogeneity in SIR epidemics modeling: superspreaders and herd immunity

Deterministic epidemic models, such as the Susceptible-Infected-Recovered (SIR) model, are immensely useful even if they lack the nuance and complexity of social contacts at the heart of network science modeling. Here we present a simple modification of the SIR equations to include the heterogeneity of social connection networks. A typical power-law model of social interactions from network science reproduces the observation that individuals with a high number of contacts, "hubs" or "superspreaders", can become the primary conduits for transmission. Conversely, once the tail of the distribution is saturated, herd immunity sets in at a smaller overall recovered fraction than in the analogous SIR model. The new dynamical equations suggest that cutting off the tail of the social connection distribution, i.e., stopping superspreaders, is an efficient non-pharmaceutical intervention to slow the spread of a pandemic, such as the Coronavirus Disease 2019 (COVID-19).

Forecasting of the SARS-CoV-2 epidemic in India using SIR model, flatten curve and herd immunity

In this paper, we are presenting an epidemiological model for exploring the transmission of outbreaks caused by viral infections. Mathematics and statistics are still at the cutting edge of technology where scientific experts, health facilities, and government deal with infection and disease transmission issues. The model has implicitly applied to COVID-19, a transmittable disease by the SARS-CoV-2 virus. The SIR model (Susceptible-Infection-Recovered) used as a context for examining the nature of the pandemic. Though, some of the mathematical model assumptions have been improved evaluation of the contamination-free from excessive predictions. The objective of this study is to provide a simple but effective explanatory model for the prediction of the future development of infection and for checking the effectiveness of containment and lock-down. We proposed a SIR model with a flattening curve and herd immunity based on a susceptible population that grows over time and difference in mortality and birth rates. It illustrates how a disease behaves over time, taking variables such as the number of sensitive individuals in the community and the number of those who are immune. It accurately model the disease and their lessons on the importance of immunization and herd immunity. The outcomes obtained from the simulation of the COVID-19 outbreak in India make it possible to formulate projections and forecasts for the future epidemic progress circumstance in India.

Responding to the COVID-19 Pandemic in Developing Countries: Lessons from Selected Countries of the Global South

Reviewing selected policy responses in Asia and South America, this paper draws pragmatic lessons for developing countries to better address the COVID-19 pandemic. It argues that not acting quickly and adequately incurs much higher costs. So-called ‘best practices’, while useful, may be inappropriate, especially if not complemented by effective and suitable socio-economic measures. Public understanding, support and cooperation, not harsh and selective enforcement of draconian measures, are critical for successful implementation of containment strategies. This requires inclusive and transparent policy-making, and well-coordinated and accountable government actions that build and maintain trust between citizens and government. In short, addressing the pandemic crisis needs ‘all of government’ and ‘whole of society’ approaches under credible leadership.

Does education about local vaccination rates and the importance of herd immunity change US parents' concern about measles?

It is unclear how broadly aware parents are of the concept of herd immunity and whether parents consider community benefits of vaccination when making decisions about their child’s vaccinations. We aimed to determine whether educating parents about community-level benefits of measles, mumps, and rubella (MMR) vaccination and local vaccination rates would impact concern about their child’s risk of measles and risk of a measles outbreak.

We conducted an electronic survey among Minnesota parents of children aged 6–18 years in August 2016. We assessed baseline knowledge of herd immunity, asked participants to estimate MMR vaccination coverage in their county, and asked participants to estimate the minimum coverage needed to prevent measles outbreaks. We then delivered a short, educational intervention via the survey to inform participants about the benefits of herd immunity, the actual MMR vaccination coverage in their county, and that at least 95% MMR vaccination coverage is needed to prevent measles outbreaks. Pre- and post-intervention, participants were asked to report how concerned they were that their child might get measles. We used logistic regression models to assess factors associated with awareness of herd immunity, change in concern about one’s child’s measles risk, and overall concern for a measles outbreak.

Among 493 participants, 67.8% were aware of herd immunity at baseline. Post-intervention, 40.2% (n = 198) of parents learned that MMR vaccination rates in their county were higher than they expected. All participants found out that their county MMR rates were lower than the measles herd immunity threshold of 95%. Overall, 27.0% (n = 133) of participants reported an increase in concern that their child might get measles after learning about local vaccination coverage and the coverage needed to achieve herd immunity.

We found that our short, educational intervention aimed to increase awareness about herd immunity and local vaccination led to an increase in concern about disease risk among less than a third of parents.

The COVID-19 pandemic through eyes of a NYC fertility center: a unique learning experience with often unexpected results

Affecting basic tenets of human existence such as health, economic as well as personal security and, of course, reproduction, the COVID-19 pandemic transcended medical specialties and professional disciplines. Yet, six months into the pandemic, there still exists no consensus on how to combat the virus in absence of a vaccine. Facing unprecedented circumstances, and in absence of real evidence on how to proceed, our organization early in the pandemic decided to act independently from often seemingly irrational guidance and, instead, to carefully follow a quickly evolving COVID-19 literature. Here described is the, likely, unique journey of a fertility center that maintained services during peaks of COVID-19 and political unrest that followed. Closely following publicly available data, we recognized relatively early that New York City and other East Coast regions, which during the initial COVID-19 wave between March and May represented the hardest-hit areas in the country, during the second wave, beginning in June and still in progress, remained almost completely unaffected. In contrast, south western regions, almost completely unaffected by the initial wave, were severely affected in the second wave. These two distinctively different infectious phenotypes suggested two likely explanations: The country was witnessing infections with two different SARS-CoV-2 viruses and NYC (along with the East Coast) acquired during the first wave much better immunity to the virus than south western regions. Both hypotheses since have been confirmed: East and West Coasts, indeed, were initially infected by two distinctively different lineages of the virus, with the East Coast lineage being 10-times more infectious. In addition, immunologists discovered an up to this point unknown long-term anti-viral innate (cellular) immune response which offers additional and much broader anti-viral immunity than the classical adaptive immunity via immobilizing antibodies that has been known for decades. Consequently, we predict that in the U.S., even in absence of an available vaccine, COVID-19, by September-October, will be at similarly low levels as are currently seen in NYC and other East Coast regions (generally < 1% test-positivity). We, furthermore, predict that, if current mitigation measures are maintained and no newly aggressive mutation of the virus enters the country, a significant fall-wave of COVID-19, in combination with the usual fall wave of influenza, appears unlikely. To continue serving patients uninterrupted throughout the pandemic, turned for all of our center's staff into a highly rewarding experience, garnered respect and appreciation from patients, and turned into an absolutely unique learning experience.