Should you get a second booster of the Pfizer vaccine? As usual, with medical questions the answer is “it depends”. Fortunately we now have excellent data on this point for those over 60. As usual the best data is from Israel, with a mere 623,335 people over 60 getting the fourth shot and 628,976 not getting it.
The short answer is that the booster will give you some protection (compared to not getting the 4th shot) against getting infected for a few weeks, but essentially no protection from infection at 6 weeks.
The headline news is that for 6 weeks the 2nd booster cuts your chance of severe COVID19 by a factor of 3. The protection against severe infection didn’t wane at 6 weeks.
The numbers in a minute, but I’m sure you’re wondering why such a short study? Because infections with the B.1.1.529 variant of omicron started surging in Israel in December. So with that in mind the Israelis began vaccinating people over 60 in January of 2022. You don’t just go and vaccinate over half a million people for fun. They had to balance the hunger for data about the help a fourth dose would give with the time needed to pass to get a meaningful study. The longer the study, the better the data, but the longer to remain in the dark.
I’m certain the study will be updated with the passage of time, but likely the number of people with only 3 doses will shrink. Also almost certainly more people in both groups will get severe COVID19
Now for the numbers: there were 355 severe cases of COVID19 in the 623,335 getting 4 doses and 1,210 cases in the 628,976 getting only 3 doses of the Pfizer vaccine. So the protection from severe illness by the fourth dose was a decrease in risk by greater than 2/3.
That’s the headline, but there is more to think about. 1/500 people getting 3 doses had severe COVID vs. 1/1500 people getting 4 doses. Neither risk is very high.
Although there was no decline in severe COVID19 protection at 6 weeks, some decline at 6 months and a year is likely (if it’s like every other vaccine that’s been studied). Even more to the point, if the first booster had not declined in protection we wouldn’t need a second. I don’t see any reason the second booster should act differently. Remember both boosters are to a virus which is no longer circulating.
So should you rush out and get that 4th shot? Again it depends. You want maximum protection when cases are surging in your area. That’s when you get the most bang for your buck.
Here in the USA, statistics are good. What you are interested in, is people admitted to hospital because of COVID19. To avoid spreading the virus, everyone admitted gets tested for the virus even if they got run over by a truck.. In this regard Massachusetts’s reporting is quite good — on 14 April ’22 there were 343 COVID19 patients in hospital statewide, but only 113 were hospitalized because of COVID19. Hopefully, your local statistics are that good.
One of the (few) benefits of the pandemic is the fact that articles about the virus and COVID19 are not behind paywalls, but freely available to all (which is good because we’re all in the same boat, and we need all the brainpower we have to evaluate the latest data).
So here’s a link to the article discussed above — https://www.nejm.org/doi/pdf/10.1056/NEJMoa2201570?articleTools=true
Chemiotics II 