Thread by @vipintukur

As a result of the emergence and circulation of antigenically distinct #SARS2 variants, a number of variant-modified #COVID19 vaccines have been developed. 1/

The researchers performed a meta-analysis of the available data on neutralisation titres from clinical studies comparing booster vaccination with either the current ancestral-based vaccines or variant-modified vaccines. 2/

They then use this to predict the relative efficacies of these booster vaccines under different scenarios.

Here are the key findings of this modelling study:

1-A large proportion of the benefit comes from receiving any booster at all (including an ancestral-based booster) 3/

2-Use of a variant-modified vaccine is expected to provide a modest increase in protection, which may be slightly greater in cases where the vaccine immunogen is more antigenically related to the circulating variant or if immunity has waned. 4/

3-However, even if the SARS2 variant circulating at the time of vaccination is relatively antigenically distant from immunogen in the variant-modified booster, an elevated level of protection (when compared to either no booster or an ancestral-based booster) is still expected 5/

4-The overall benefit of variant-modified vaccines will likely be determined by other factors, including the time since vaccination (waning of immunity), relative availability, cost & community acceptance of these vaccines over existing vaccines 6/

medrxiv.org/content/10.110…