Thread by @FLAHAULT

1/9 - “[A new study] suggests that updated boosters [of #COVID19 vaccines] seem to offer much the same protection as an extra dose of the older vaccines — particularly when it comes to keeping people out of hospital.”
nature.com/articles/d4158…

2/9 - “On 15 August, the United Kingdom became the first country to approve these ‘bivalent’ vaccines, which are based on the #Omicron #BA1 lineage and the original #SARSCoV2 sequence identified in Wuhan, China, and will soon roll them out. [And today EMA].”

3/9 - “Largescale efficacy trials […] which involved randomly assigning tens of thousands of people to get a vaccine or placebo and following who got infected are no longer practical, possible or ethical in 2022.”

4/9 - “Updated #COVID19 vaccines have instead been trialled in smaller groups. To gauge effectiveness, developers have typically measured participants’ immune responses, particularly infection-blocking ‘neutralizing’ antibodies, and compared them with […] the original vaccine.”

5/9 - “Most of these trials found that updated vaccines — based not only #Omicron, but also older variants including Beta — performed a bit better in this measure than the original vaccines. “This is a clearly superior booster,” Moderna’s president, Stephen Hoge, told investors.”

6/9 - “Studies suggest that higher levels of neutralizing antibodies equate to better protection against #COVID19. But it wasn’t clear from the updated vaccine trials how much more effective they might be.”

7/9 - “Bivalent vaccines that included the original vaccine looked no more effective than vaccines based solely on a newer variant. […] the main message of the analysis should be that any #COVID19 booster is a good one.”

8/9 -“Other scientists question the decision to pursue variant boosters, when the benefit is so small. Worry that people are being misled into thinking updated vaccines are vastly more effective than existing vaccines, and might then expose themselves to greater infection risks.”

9/9 - “In the long run, it probably makes sense to develop variant-based vaccines, but the idea that they need to closely match circulating viral strains is unrealistic and counterproductive when highly effective vaccines are already available.”