Live viral vaccines in immunocompromised patients

Safety of mRNA COVID ‐19 vaccines in patients with well controlled myasthenia gravis

Introduction/Aims

Data on safety and tolerability of the vaccines against severe acute respiratory virus coronavirus‐2 (SARS‐CoV‐2, or coronavirus disease‐2019 [COVID‐19]) in patients with myasthenia gravis (MG) are currently limited. In this study we investigated the safety of mRNA‐based two‐dose vaccination in a cohort of patients with MG.

Methods

This investigation was a prospective observational study of messenger RNA (mRNA)‐based vaccines administered to patients with MG with stable disease. Local and systemic reactogenicity after injection was monitored for each dose administered. The patients were categorized and clinically assessed following the recommendations of the Myasthenia Gravis Foundation of America.

Results

Thirty‐six males and 55 females (mean age at first vaccine dose, 58.8 years; standard deviation, = 17.1 years) received vaccines. Seventy‐two patients (79.1%) were taking one or more immunosuppressant(s). The most frequent adverse effects were injection‐site pain, fatigue, myalgia, chills, fever, and headache. Local and systemic reactions were transient; 58.2% of the patients developed one or more reaction(s). There were no anaphylactic reactions. None of the patients had a myasthenic crisis, and two developed a mild deterioration compared with their Quantitative Myasthenia Gravis baseline score. The clinical outcome scores showed no exacerbation of MG symptoms. Patients over 65 years of age developed fewer adverse effects. COVID‐19 vaccination did not induce clinical exacerbation in stable patients with MG, regardless of their age, sex, history of myasthenic crisis, or whether they were taking immunosuppressants.

Discussion

Our data are consistent with the mRNA COVID‐19 vaccine being well tolerated in patients with well‐controlled MG. The findings may contribute to decisions in vaccination campaigns in the future.

Herpes Simplex Viruses Whose Replication Can Be Deliberately Controlled as Candidate Vaccines

Over the last few years, we have been evaluating a novel paradigm for immunization using viruses or virus-based vectors. Safety is provided not by attenuation or inactivation of vaccine viruses, but by the introduction into the viral genomes of genetic mechanisms that allow for stringent, deliberate spatial and temporal control of virus replication. The resulting replication-competent controlled viruses (RCCVs) can be activated to undergo one or, if desired, several rounds of efficient replication at the inoculation site, but are nonreplicating in the absence of activation. Extrapolating from observations that attenuated replicating viruses are better immunogens than replication-defective or inactivated viruses, it was hypothesized that RCCVs that replicate with wild-type-like efficiency when activated will be even better immunogens. The vigorous replication of the RCCVs should also render heterologous antigens expressed from them highly immunogenic. RCCVs for administration to skin sites or mucosal membranes were constructed using a virulent wild-type HSV-1 strain as the backbone. The recombinants are activated by a localized heat treatment to the inoculation site in the presence of a small-molecule regulator (SMR). Derivatives expressing influenza virus antigens were also prepared. Immunization/challenge experiments in mouse models revealed that the activated RCCVs induced far better protective immune responses against themselves as well as against the heterologous antigens they express than unactivated RCCVs or a replication-defective HSV-1 strain. Neutralizing antibody and proliferation responses mirrored these findings. We believe that the data obtained so far warrant further research to explore the possibility of developing effective RCCV-based vaccines directed to herpetic diseases and/or diseases caused by other pathogens.

Prevention of yellow fever in travellers: an update

For centuries, yellow fever virus infection generated substantial fear among explorers, tourist travellers, workers, military personnel, and others entering areas of transmission. Currently, there is transmission only in some areas of tropical South America and sub-Saharan Africa. When symptomatic, yellow fever infection causes severe liver dysfunction and coagulopathy with elevated mortality rates. Since there is no effective treatment, vaccination against yellow fever, available since 1937, represents an important preventive intervention in endemic areas. Every year, an increasing number of individuals are travelling to yellow fever endemic areas, many of whom have complex medical conditions. Travel health practitioners should do individualised assessments of the risks and benefits of yellow fever vaccination to identify potential contraindications. The most relevant contraindications include a history of thymoma or thymus dysfunction, AIDS, and individuals receiving immunosuppressive drugs including biological therapies or chemotherapy. We briefly review strategies to prevent yellow fever infection in travellers with the use of yellow fever vaccination and the use of personal protection measures to avoid mosquito bites.

Autoimmune disease and vaccination: impact on infectious disease prevention and a look at future applications

Vaccines hold promise both for the prevention of infections and as potential immunologic therapy for patients with autoimmune disease (AD). These patients are at high risk for both common and opportunistic infections, but this risk can be significantly reduced and even obviated with the use of recommended available vaccines. Unfortunately, patients with ADs are not routinely offered or provided indicated vaccinations and have higher rates of complications from vaccine-preventable illnesses than patients without ADs. In addition, vaccine therapy is currently under study for the treatment of autoimmune disorders, with early studies demonstrating immunomodulatory effects that may counter undesired immune activation and alleviate disease activity.