Over a year on since the coronavirus disease 2019 (COVID-19) pandemic began, evidence from studies suggests that the deployment of physical preventive measures, including social distancing, lockdowns, face mask usage, and handwashing, are not fully effective in preventing or mitigating the impact of social distancing on health, society, and the economy.
Thus, universal vaccine rollout is the ultimate tool for limiting hospitalization and deaths associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and also for controlling viral transmission and mutation. Currently approved COVID-19 vaccines contain inactivated virus, viral proteins such as the spike protein, viral DNA, or viral mRNA.
Data shows that different vaccines have different efficacies, between 85 and 100%, in preventing severe COVID-19 illness caused by the original strain, while showing relatively lower efficacy of between 50 and 80% in patients infected by SARS-CoV-2 variants of concern (VOC). Studies have shown significant variability in inefficacies of COVID-19 vaccines among individuals, mostly due to the heterogeneous immune response in vaccine recipients. Therefore, it would be helpful to monitor vaccine efficacy in some form so as to predict individual and community immunogenicity and hence the efficacy in potential recipients.
Monitoring anti-SARS-CoV-2 antibodies in vaccine recipients prior to and after receiving COVID-19 vaccination
An opinion paper by researchers from the US and Italy recently discussed various aspects of monitoring anti-SARS-CoV-2 antibodies before and after receiving COVID-19 vaccination to highlight the pros and cons of this monitoring strategy. This paper is published in the open-access journal Diagnostics.
The discussion highlights the advantages of testing anti-SARS-CoV-2 antibodies in COVID-19 vaccine recipients, including early identification of low or non-responders to COVID-19 vaccination, assessing baseline seroprevalence of SARS-CoV-2 infection in non-vaccinated individuals and timely detection of faster decay of anti-SARS-CoV-2 antibody levels.
In contrast, a potential drawback of a widespread serosurveillance strategy includes an unproven relationship between antibody titer against SARS-CoV-2, neutralizing activity, and efficiency of vaccines. Major challenges in universal anti-SARS-CoV-2 antibodies testing include a lack of cost-effective analyses of various testing strategies, the huge volume of blood drawings needed, and increased lab workload.
Testing costs vary across geographies and, hence, a universal approach may not be feasible. Local simulation studies, where it is easier to calculate the overall costs based on available resources, number of total samples, type of vaccine, type of anti-SARS-CoV-2 immunoassay, cost of staff and sample delivery, may work better.
A possible solution might involve identifying groups that need to be prioritized for testing like those at higher risk of exposure and infection by SARS-CoV-2 variants of concern, vulnerable population such as the elderly, cancer patients, people undergoing immunosuppressive treatments, patients with severe renal impairment, or obese people who are at higher risk of progression to severe disease, and individuals with lower or shorter vaccine immunogenicity.
Discussion highlights economic, biological, and logistical challenges involved in post-vaccination serosurveillance strategy
Although anti-SARS-CoV-2 antibody testing in COVID-19 vaccine recipients offers several clinical advantages, many important economic, biological, and logistical challenges are involved in this strategy.
While a definitive conclusion in favor of the strategy cannot be drawn based on evidence gathered so far, the authors believe that this analysis may persuade healthcare administrators, policymakers, clinicians, and lab professionals to deploy multi-disciplinary teams that can work on defining the local cost-effectiveness of post-vaccination serosurveillance campaigns. Identification of priority cohort for testing based on population at risk of infection by variants of concern or older adults with low immunogenicity could help address these challenges to an extent.
The team writes:
Notably, the recent claim made by the WHO stating that international COVID-19 trials shall be restarted with more focus on immune response provides significant support to targeted anti-SARS-CoV-2 antibodies testing for assessing the effectiveness of existing treatments, thus including vaccinations.”