Vaccines vs. Variants. COVID-19 Research Summary

Samples of blood from patients who have received two doses of the Pfizer/BioNTech vaccine (BNT162b2) were collected by researchers. The antibodies in these are able to neutralise all the major currently circulating variants of SARS-CoV-2.

The UK (B.1.1.7) and Brazilian (P.1) variants show no or a modest reduction in effectiveness, whereas the South African (B.1.351) variant showed the largest reduction. The level of neutralisation of B.1.351 is still “robust” according to the authors. In addition, they note that the results after two doses are significantly improved compared to one dose. [1]

Neutrilisation titres of sera collected from patients inoculated with two doses of BNT162b2. Source: [1]

In line with the corresponding results of the SIREN trial on healthcare workers in the NHS, a study in Denmark finds that previous infection provides ~80 % protection against re-infection. This rapidly declines in older populations (estimated ~45%; upper bound ~60%). [2,3]

Re-infection data from Denmark, evaluating the protection conferred by infection with SARS-CoV-2. Source: [2]

Researchers in the US compared the rates of asymptomatic infection between vaccinated and unvaccinated patients (mRNA vaccines). They found that once the vaccine had caused an immune response (>10 days after first dose), the vaccinated patients were ~70 % less likely to suffer from asymptomatic infection. [4]

Outcomes of the study of asymptomatic incidence in patients vaccinated with mRNA vaccines. Source: [4]

A similar study in the UK involving healthcare workers found similar outcomes. [5]

The vaccine candidate from J&J (Janssen) has received an EUA from the FDA. [6]

Ad26.COV2.S was shown to be ~65 % effective in a phase III clinical trial. Notably, this vaccine is administered in only one dose. [7]

Primary endpoint analyses for J&J’s vaccine candidate Ad26.COV2.S. Source: [7]

References

1. https://www.nejm.org/doi/pdf/10.1056/NEJMc2102017?articleTools=true
2. https://www.thelancet.com/action/showPdf?pii=S0140-6736%2821%2900575-4
3. https://michaelbogdos.medium.com/vaccines-and-sars-cov-2-variants-natural-vs-vaccine-immunity-1d9e8b39e38e
4. https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab229/6167855
5. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3790399
6. https://www.fda.gov/news-events/press-announcements/fda-issues-emergency-use-authorization-third-covid-19-vaccine
7. https://www.fda.gov/media/146217/download