The Pfizer vaccine also works well in practice

Even in a large-scale real-world vaccination campaign, the sky-high protection against Covid-19 provided by Pfizer’s vaccine remains. That is even better than the 95 percent protection against disease that the first studies showed, according to Israeli research into the first four months of the vaccination campaign in that country, published this week in the scientific journal. The Lancet.

Two weeks after the second shot, the vaccine not only offers 98 percent protection against hospitalization and death from Covid-19, but also over 96 percent against an infection – with or without symptoms. Until now it was unclear whether vaccination could prevent that. The protection of the elderly in all these areas was comparable. And that in a country where the British virus variant, B.1.1.7, causes by far the most infections.

The Israeli study is the first to show the effect of a vaccination program with this drug on public health. Israel is a global leader in corona vaccinations. On April 3, 72 percent of the population over the age of 16 was fully vaccinated. The country only used the Pfizer vaccine during the period of the study, between January 24 and April 3. Previously, preliminary estimates of the effect of this vaccine in the ‘real world’ were already released from various countries.

Out of the pandemic

In this study, led by the Israeli counterpart of the RIVM, the researchers also looked at the protection after one dose, in the second week after the injection. It turned out to be clearly less: there was almost 58 percent protection against infection, and 76 to 77 percent against hospitalization and death. A complete vaccination, with two doses, is thus clearly more effective.

While the percentage of people vaccinated was increasing rapidly, the number of corona infections in Israel decreased dramatically. That shows that high vaccination coverage provides a way out of the pandemic, researchers Eyal Leshem and Annelies Wilder-Smith, who are not involved in the study, write in an accompanying commentary. They regret that this will not be easily achievable for many countries, if only because of the limited availability, high cost and ice-cold storage temperature of the Pfizer vaccine.

It is still unknown how long the immune system will persist after infection or vaccination

The results are very encouraging, but there are also many questions and uncertainties, Israeli researchers emphasize. For example, it is still unknown how long the resistance against the virus will persist after infection or after vaccination. In the latest analyzes of a large phase 3 study, that was at least 6 months, the manufacturer writes in a press release – the results have not yet been published.

It is also not yet clear to what extent the built-up immune system protects against new virus variants, such as those that have emerged in South Africa, Brazil and other countries.

Research to date has shown that the protection against the South African variant, B.1.351, is somewhat lower, but still sufficient. In Qatar, where the British and South African variants are circulating in about equal proportions, full vaccination with the Pfizer vaccine still provided 75 percent protection against infection with the South African variant, and about 90 percent against infection with the British. Against severe and fatal Covid-19, by whatever variant, researchers also saw more than 97 percent protection here, according to Wednesday in the scientific journal NEJM published research. In Qatar, nearly 400,000 people were vaccinated between December and March 31, of which more than 260,000 had already received two doses of the Pfizer shot.

South African variant

Also in one study not yet peer-reviewed Another group of Israeli researchers recently found indications that the vaccine is slightly less effective against the South African virus variant.

Previous laboratory studies also point in that direction. Lab versions of the South African variety to escape the antibodies in the blood of ex-Covid-19 patientsunless they are present in very high amounts.

But in one other study, with blood from people vaccinated with Pfizer, antibodies flattened a lab version of the South African variant slightly less well, but still more than sufficiently.

Pfizer is working on a modified version of the vaccine that will also protect against the new variants.