SARS CoV-2 Seroprevalence in Selected States of High and Low Disease Burden in Nigeria

SARS-CoV and SARS-CoV -2 cross-reactive antibodies in domestic animals and wildlife in Nigeria suggest circulation of sarbecoviruses

Anthropogenic exposure of domestic animals, as well as wildlife, can result in zoonotic transmission events with known and unknown pathogens including sarbecoviruses. During the COVID-19 pandemic, SARS-CoV-2 infections in animals, most likely resulting from spill-over from humans, have been documented worldwide. However, only limited information is available for Africa. The anthropozoonotic transmission from humans to animals, followed by further inter- and intraspecies propagation may contribute to viral evolution, and thereby subsequently alter the epidemiological patterns of transmission. To shed light on the possible role of domestic animals and wildlife in the ecology and epidemiology of sarbecoviruses in Nigeria, and to analyze the possible circulation of other, undiscovered, but potentially zoonotic sarbecoviruses in animals, we tested 504 serum samples from dogs, rabbits, bats, and pangolins collected between December 2020 and April 2022. The samples were analyzed using an indirect multi-species enzyme-linked immunosorbent assay (ELISA) based on the receptor binding domain (RBD) of SARS-CoV and SARS-CoV -2, respectively. ELISA reactive sera were further analyzed by highly specific virus neutralization test and indirect immunofluorescence assay for confirmation of the presence of antibodies. In this study, we found SARS-CoV reactive antibodies in 16 (11.5%) dogs, 7 (2.97%) rabbits, 2 (7.7%) pangolins and SARS-CoV-2 reactive antibodies in 20 (13.4%) dogs, 6 (2.5%) rabbits and 2 (7.7%) pangolins, respectively. Interestingly, 2 (2.3%) bat samples were positive only for SARS-CoV RBD reactive antibodies. These serological findings of SARS-CoV and/or SARS-CoV-2 infections in both domestic animals and wildlife indicates exposure to sarbecoviruses and requires further One Health-oriented research on the potential reservoir role that different species might play in the ecology and epidemiology of coronaviruses at the human-animal interface.

High pre-Delta and early-Omicron SARS-CoV-2 seroprevalence detected in dried blood samples from Kinshasa (D.R. Congo)

Studies on the impact of the COVID-19 pandemic in sub-Saharan Africa have yielded varying results, although authors universally agree the real burden surpasses reported cases. The primary objective of this study was to determine SARS-CoV-2 seroprevalence among patients attending Monkole Hospital in Kinshasa (D.R. Congo). The secondary objective was to evaluate the analytic performance of two chemiluminescence platforms: Elecsys® (Roche) and VirClia® (Vircell) on dried blood spot samples (DBS). The study population (N = 373) was recruited in two stages: a mid-2021 blood donor cohort (15.5% women) and a mid-2022 women cohort. Crude global seroprevalence was 61% (53.9%-67.8%) pre-Delta in 2021 and 90.2% (84.7%-94.2%) post-Omicron in 2022. Anti-spike (S) antibody levels significantly increased from 53.1 (31.8-131.3) U/mL in 2021 to 436.5 (219.3-950.5) U/mL in 2022 and were significantly higher above 45 years old in the 2022 population. Both platforms showed good analytic performance on DBS samples: sensitivity was 96.8% for IgG (antiN/S) (93.9%-98.5%) and 96.0% (93.0%-98.0%) for anti-S quantification. These results provide additional support for the notion that exposure to SARS-CoV-2 is more widespread than indicated by case-based surveillance and will be able to guide the pandemic response and strategy moving forward. Likewise, this study contributes evidence to the reliability of DBS as a tool for serological testing and diagnosis in resource-limited settings.

Coronavirus Disease 2019 Vaccination Coverage and Seropositivity amongst Nigerians 18 Years Old and Above

BACKGROUND

This was a cross-sectional community-based survey to study the prevalence of serum antibodies against the severe acute respiratory syndrome coronavirus 1 (SARS-COV-1) and determine possible source of antibodies as to whether from vaccination or from natural infection as well as attempt to compare antibody levels in response to the different four types of vaccines administered in Nigeria.

METHODS

A cross-sectional community-based study of the prevalence of serum antibodies against all four vaccine types used in Nigeria amongst a representative sample of people aged 18 years and above in the six geopolitical zones of the country using a multistage sampling technique covering 12 states of the country with two states being randomly selected from each geopolitical zone. High-throughput Roche electrochemiluminescence immunoassay system (Elecsys Anti-SARS-COV-1 Cobas) was used for qualitative and quantitative detection of antibodies to SARS-COV-1 in human plasma.

RESULTS

There was no statistically significant difference between the proportions with seropositivity for both the vaccinated and the unvaccinated (P = 0.95). The nucleocapsid antibody (anti-Nc) titres were similar in both the vaccinated and the unvaccinated, whereas the Spike protein antibody (anti-S) titres were significantly higher amongst the vaccinated than amongst the unvaccinated. Antibody levels in subjects who received different vaccines were compared to provide information for policy.

CONCLUSION

While only 45.9% of the subjects were reported to have been vaccinated, 98.7% of the subjects had had contact with the SARS-COV-1 as evidenced by the presence of nucleocapsid (NC) antibodies in their plasma. The 1.3% who had not been exposed to the virus, had spike protein antibodies which most likely resulted from vaccination in the absence of NC antibodies. Successive vaccination and booster doses either through heterogeneous or homologous vaccines increased antibody titres, and this stimulation of immune memory may offer greater protection against coronavirus disease 2019.

Comparison of in-hospital mortality in children and adolescents with sickle cell disease in a resource-limited setting before and during the COVID-19 pandemic

BACKGROUND

COVID-19 in children and adolescents with sickle cell disease (SCD) has variable presentations (from mild to severe disease), and the main symptoms are vaso-occlusive crises (VOC) and acute chest syndrome (ACS). We hypothesized that the desertion of hospitals due to the pandemic would lead to late arrival at the emergency room and an increased mortality. In this study, we sought to measure and compare the mortality of children with sickle cell disease before and during the COVID-19 pandemic.

MATERIAL AND METHODS

We conducted a retrospective cohort study at the sickle cell disease management center of Laquintinie Hospital in Douala (Cameroon). The study period was divided into two, i.e., from March 2019 to February 2020 (Pre-COVID-19) and from March 2020 to February 2021 (COVID-19). All administrative and ethical considerations were fully respected. Data were analyzed using SPSS 20.0.

RESULTS

Overall, 823 patients were admitted during the study period. Males represented 52.4% of the overall population, giving a sex ratio of 1.1:1. We admitted 479 patients during the pre-COVID-19 period versus 344 patients during the COVID-19 period, which is a 28.2% drop in admissions during the COVID-19 period. The mortality rate was 3.5% during the pre-COVID-19 period and 3.2% during the COVID-19 period (p>0.05). The most common causes of death were ACS (39.3%, n = 11), severe anemia (25.0%, n = 7), and VOC (17.9%, n = 5). ACS (adjusted odds ratio [aOR]=3.628, 95% confidence interval [CI], [1.645-7.005], p<0.001) was significantly associated with mortality.

CONCLUSION

During the COVID-19 pandemic, although the consultation frequency decreased, the mortality rate of sickle cell disease patients remained unchanged.

High SARS-CoV-2 seroprevalence in Lagos, Nigeria with robust antibody and cellular immune responses

Background

Early evidence suggested that the impact of the COVID-19 pandemic was less severe in Africa compared to other parts of the world. However, more recent studies indicate higher SARS-CoV-2 infection and COVID-19 mortality rates on the continent than previously documented. Research is needed to better understand SARS-CoV-2 infection and immunity in Africa.

Methods

In early 2021, we studied the immune responses in healthcare workers (HCWs) at Lagos University Teaching Hospital (n = 134) and Oxford-AstraZeneca COVID-19 vaccine recipients from the general population (n = 116) across five local government areas (LGAs) in Lagos State, Nigeria. Western blots were used to simultaneously detect SARS-CoV-2 spike and nucleocapsid (N) antibodies (n = 250), and stimulation of peripheral blood mononuclear cells with N followed by an IFN-γ ELISA was used to examine T cell responses (n = 114).

Results

Antibody data demonstrated high SARS-CoV-2 seroprevalence of 72·4% (97/134) in HCWs and 60·3% (70/116) in the general population. Antibodies directed to only SARS-CoV-2 N, suggesting pre-existing coronavirus immunity, were seen in 9·7% (13/134) of HCWs and 15·5% (18/116) of the general population. T cell responses against SARS-CoV-2 N (n = 114) were robust in detecting exposure to the virus, demonstrating 87·5% sensitivity and 92·9% specificity in a subset of control samples tested. T cell responses against SARS-CoV-2 N were also observed in 83.3% of individuals with N-only antibodies, further suggesting that prior non-SARS-CoV-2 coronavirus infection may provide cellular immunity to SARS-CoV-2.

Conclusions

These results have important implications for understanding the paradoxically high SARS-CoV-2 infection with low mortality rate in Africa and supports the need to better understand the implications of SARS-CoV-2 cellular immunity.

COVID-19 Vaccine Hesitancy: A Content Analysis of Nigerian YouTube Videos

Vaccination is key to developing herd immunity against COVID-19; however, the attitude of Nigerians towards being vaccinated stalled at the 70% vaccination target. This study engages Theory of Planned Behaviour to analyse the tone of Nigerian YouTube headlines/titles, and the tone of YouTube users' comments to examine the causes of COVID-19 vaccine hesitancy. YouTube videos uploaded between March 2021 and December 2022 were analysed using a content analytic approach. Results show 53.5% of the videos had a positive tone, while 40.5% were negative, and 6% neutral. Second, findings indicate most of the Nigerian YouTube users' comments were neutral (62.6%), while 32.4%, were negative, and 5% were positive. From the antivaccine themes, analysis shows the people's lack of trust in the government on vaccines (15.7%) and the presence of vaccine conspiracy theories mostly related to expressions of religion and biotechnology (46.08%) were the main causes of COVID-19 vaccine hesitancy in Nigeria. The study presents implications for theory and recommends ways for governments to develop better vaccination communication strategies.

Omicron B.1.1.529 variant infections associated with severe disease are uncommon in a COVID-19 under-vaccinated, high SARS-CoV-2 seroprevalence population in Malawi

Background

The B.1.1.529 (Omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in the fourth COVID-19 pandemic wave across the southern African region, including Malawi. The seroprevalence of SARS-CoV-2 antibodies and their association with epidemiological trends of hospitalisations and deaths are needed to aid locally relevant public health policy decisions.

Methods

We conducted a population-based serosurvey from December 27, 2021 to January 17, 2022, in 7 districts across Malawi to determine the seroprevalence of SARS-CoV-2 antibodies. Serum samples were tested for antibodies against SARS-CoV-2 receptor binding domain using WANTAI SARS-CoV-2 Receptor Binding Domain total antibody commercial enzyme-linked immunosorbent assay (ELISA). We also evaluated COVID-19 epidemiologic trends in Malawi, including cases, hospitalisations and deaths from April 1, 2021 through April 30, 2022, collected using the routine national COVID-19 reporting system. A multivariable logistic regression model was developed to investigate the factors associated with SARS-CoV-2 seropositivity.

Findings

Serum samples were analysed from 4619 participants (57% female; 60% aged 18-50 years), of whom 878/3794 (23%) of vaccine eligible adults had received a single dose of any COVID-19 vaccine. The overall assay-adjusted seroprevalence was 83.7% (95% confidence interval (CI), 79.3%-93.4%). Seroprevalence was lowest among children <13 years of age (66%) and highest among adults 18-50 years of age (82%). Seroprevalence was higher among vaccinated compared to unvaccinated participants (1 dose, 94% vs. 77%, adjusted odds ratio 4.89 [95% CI, 3.43-7.22]; 2 doses, 97% vs. 77%, aOR 6.62 [95% CI, 4.14-11.3]). Urban residents were more likely to be seropositive than those from rural settings (91% vs. 78%, aOR 2.76 [95% CI, 2.16-3.55]). There was at least a two-fold reduction in the proportion of hospitalisations and deaths among the reported cases in the fourth wave compared to the third wave (hospitalisations, 10.7% (95% CI, 10.2-11.3) vs. 4.86% (95% CI, 4.52-5.23), p < 0.0001; deaths, 3.48% (95% CI, 3.18-3.81) vs. 1.15% (95% CI, 1.00-1.34), p < 0.0001).

Interpretation

We report reduction in proportion of hospitalisations and deaths from SARS-CoV-2 infections during the Omicron variant dominated wave in Malawi, in the context of high SARS-CoV-2 seroprevalence and low COVID-19 vaccination coverage. These findings suggest that COVID-19 vaccination policy in high seroprevalence settings may need to be amended from mass campaigns to targeted vaccination of reported at-risk populations.

Funding

Supported by the Bill and Melinda Gates Foundation (INV-039481).

SARS-CoV-2 antibody seroprevalence in Togo: a national cross-sectional household survey, May-June, 2021

BACKGROUND

The extent of SARS-CoV-2 circulation in African countries is still unclear. Seroprevalence studies are a common approach to epidemiological surveillance, allowing estimation of the proportion of people who have had contact with the virus. We aimed at estimating the seroprevalence of anti-SARS-CoV-2 antibodies and associated factors in Togo at the national level in 2021 according to age groups, gender, and place of residence (rural or urban).

METHODS

From 15 May to 31 June 2021, we conducted a nationally representative cross-sectional serological survey in 12 health districts (two districts per health region) in the > 5 years old population in Togo. The Wantai SARS-CoV-2 total antibody assay S protein receptor-binding domain-based ELISA (Wantai Biological Pharmacy Enterprise Co.; Beijing, China) was used to determine the presence of SARS-CoV-2 total antibodies in plasma. Crude and weighted seroprevalences (weighted by age, sex and place of residence) were calculated and then weighted seroprevalences were adjusted according to sensitivity and specificity of the ELISA test. Finally, logistic regression models were performed in order to describe factors associated.

RESULTS

Of the 7593 participants, the overall weighted and adjusted seroprevalence of total anti-SARS-CoV-2 antibodies was 65.5% (CI95%: 18.9-21.1). Urban dwellers, young adults (30-49 years) and vaccinated individuals were significantly more likely to be seropositive.

CONCLUSION

The high seroprevalence we observed is consistent with observations across West Africa. Quantification of the level of immunity in the population is needed to know how close we are to herd immunity. In the meantime, vaccination against the COVID-19 remains necessary.