A SEVERAL MONTHS ago the biggest question was about covid-19 vaccines or would any of them work. In some countries, the problem today is too much to choose from. In Europe, some people encourage AstraZeneca’s jab and prefer to wait for Pfizer’s or Moderna’s instead.
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Such preferences stem from the results of clinical trials. Moderna and Pfizer, which make the same type of vaccine, announced an efficiency of 94-95%, while Johnson & Johnson and AstraZeneca reported 63-66%. French President Emmanuel Macron called AstraZeneca’s sample as a parent a quasi-inefficiency.
However, the gap in reported efficacy may say more about the trials than about the vaccines themselves. Some studies have considered people with mild symptoms to be positive cases; others have not. Those with lower reported efficacy used participants in countries where partially immune-resistant variants of SARS–CoV-2 is common. One tested only a single dose treatment.
Fortunately, apple-to-apple comparison is now possible, based on millions of people receiving different vaccines in the same country at the same time. And recent data from Britain, which gave Pfizer or AstraZeneca’s push to 20 million people, paints a different picture than the test results. Three studies show that single doses of the two samples are just as effective.
The latest paper, a preview for the Lancet published on March 3, it was found that one dose of one of the two jab was 80% protected against hospitalization in people aged at least 80 years, from 14 days after vaccination. Another study, in Scotland, included younger age groups and also found that the two jabs had similar strengths compared to hospitalization.
For a virus looking for new hosts, this is bad news – which will only get worse. Few people in Britain received second doses. However, Israel has almost completed a two-dose mass vaccination program using the Pfizer vaccine. According to the latest data from Israel, two doses are approximately 90% protective against any form of covid-19, including asymptomatic infection.
Pfizer’s sting is expensive and must be stored in freezers. In contrast, AstraZeneca’s are inexpensive and require only normal cooling. If the AstraZeneca vaccine also matches the effectiveness of Pfizer, which now seems likely, it could play a leading role in ending the pandemic – as long as people do not reject it based on unfounded swipes like Macron.■
Sources: “BNT162b2 mRNA covid-19 vaccine in a nationwide mass vaccination environment”, by N. Dagan et al., 2021; studies conducted by Public Health England and Public Health Scotland; company press releases; The Economist
This article appears in the Graphic Detail section of the print edition under the heading “Six of One”