The UK Health Security Agency reported encouraging research on booster doses. The booster reduced the risks of Covid-19 disease in people over 50 by around 85%, according to an analysis.
A booster gave the same protection after two Pfizer/BioNTech doses. The reduction occurred regardless of the initial vaccine, suggesting Oxford/AstraZeneca vaccinees have more protection after the booster dose than ever.
Estimates about the effectiveness of boosters are produced by two types of study. The Office for National Statistics Covid infections survey showed that the chance of testing positive after a booster was similar to the Pfizer/BioNTech jab. The UKHSA compared the vaccination histories of 106,000 people who tested positive and 165,000 who tested negative. That design is used in many vaccine studies to make sure that people who are vaccine free are tested for their tendencies to be unvaccinated. After 20 weeks, the effectiveness of the Pfizer/BioNTech doses waned to 92.7% from 99.7%. The estimated decline for people over 16 may not sound like much, but if we look at it in terms of lack of protection, their vulnerability relative to being unvaccinated went from 3% to 7.3%. It is a major increase in risk.
Negative framing can change impressions, for example, "90% fat-free" sounds different than "10 fat". The importance of waning immunity might be reflected in this framing, as it shows the power of third doses to lower hospital admissions.
The impact depends on the absolute risks of Covid-19. Between people and even from day to day in the same person, these viral risks add up over a year. Vaccines help others and make small risks lower. Booster doses are very effective according to early analyses.
The Winton Centre for Risk and Evidence Communication is chaired by David Spiegelhalter. The Royal Statistical Society has a statistical ambassador.
