ONE FEW MONTHS ago, the biggest question about covid-19 vaccines was whether any of them would work. Today, the problem in some countries is having too many to choose from. In Europe, some people are rejecting the AstraZeneca jab, preferring to wait for the Pfizer or Moderna jab.
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These preferences stem from the results of clinical trials. Moderna and Pfizer, which manufacture the same type of vaccine, reported 94-95% efficacy, while Johnson & Johnson and AstraZeneca reported 63-66%. Emmanuel Macron, the president of France, criticized the AstraZeneca jab as “almost ineffective” in older patients.
However, the reported effectiveness gap may say more about the tests than about the vaccines themselves. Some studies have counted people with mild symptoms as positive cases; others do not. Those with lesser reported efficacy used participants in countries where variants partially resistant to the immune system of SARS–ÇTheV-2 are common. One tested only a single dose regimen.
Fortunately, identical comparisons are now possible, based on millions of people who received different vaccines in the same country at the same time. And recent data from Britain, which gave Pfizer or AstraZeneca jabs to 20 million people, paint a different picture of the test results. Three studies show that single doses of the two jabs are equally effective.
The last paper, a pre-press for the Lancet published on March 3, found that a dose of any vaccine is 80% protective against hospitalization in people at least 80 years old, starting 14 days after vaccination. Another study in Scotland included younger age groups and also found that the two jabs had similar potency against hospitalization.
For a virus looking for new hosts, this is bad news – it will only get worse. Few people in Britain received the second dose. However, Israel almost ended a two-dose mass vaccination program using the Pfizer vaccine. According to the latest data from Israel, two doses protect about 90% against any form of covid-19, including asymptomatic infection.
The Pfizer jab is expensive and should be stored in freezers. In contrast, AstraZeneca is inexpensive and needs only normal cooling. If the AstraZeneca vaccine also matches Pfizer’s effectiveness, which now seems likely, it could play an important role in ending the pandemic – as long as people don’t reject it based on unfounded scams from people like Macron.■
Sources: “BNT162b2 mRNA covid-19 vaccine in a national mass vaccination scenario”, by N. Dagan et al., 2021; studies by Public Health England and Public Health Scotland; company press releases; The Economist
This article appeared in the graphic details section of the print edition under the heading “Six of one”