Importance of booster vaccine to protect against emergent COVID-19 variants
Kirk Taylor, HIV i-Base
A small study showing the importance of booster vaccination to protect against COVID-19 variants by researchers from Ohio University was published as a letter in the 15 June edition of the NEJM. 
Neutralising antibody (nAb) titres against different COVID-19 strains were analysed from stored serum samples. Participants were healthcare workers that had been triple vaccinated with Moderna (n=4) or Pfizer (n=11) mRNA vaccines. Additional samples from people admitted to ICU during the delta wave (n=18) or hospitalised during omicron wave (n=30) were also studied.
Compared to the D416G COVID-19 strain, nAb titres were 4.1-fold and 3.2-fold lower against BA.4/5 and BA.2.12.1 variants, respectively (p<0.001).
Overall, nAb titres against emergent strains were lowest in twice vaccinated participants. Boosting or previous COVID-19 disease generated greater levels of nAbs compared to unboosted individuals.
This is a short letter to NEJM that concerns an important topic, but it is important to note that the sample sizes are low.
Boosting of immune responses following COVID-19, is strain-dependent. A study of 700 triple vaccinated healthcare workers in the UK reports that immune boosting is lower for omicron than compared to other variants. 
These data highlight the importance of receiving COVID-19 boosters as required by local vaccination programmes.
- Qu P et al. Neutralization of the SARS-CoV-2 omicron BA.4/5 and BA.2.12.1 subvariants. NEJM. DOI: 10.1056/NEJMc2206725 (15 Jun 2022).
- Reynolds CJ et al. Immune boosting by B.1.1.529 (Omicron) depends on previous SARS-CoV-2 exposure. Science. DOI: 10.1126/science/abq1841 (14 Jun 2022).
This report was first published on 26 June 2022.