As the Delta strain spreads to Israel, the world’s most immunized country, the effectiveness of coronavirus vaccines in the prevention of infection seems to decrease considerably according to the data released by the Israeli Ministry of Health. The Israeli-American scientist from Columbia University Yaniv Erlich, based on numbers provided by the Tel Aviv government tweeted: Delta variant, bad news from Israel: Ministry of Health reports Pfizer’s effectiveness for protecting against Delta variant drops to 64% from 94% against other strains . This has important implications for herd immunity and the ability of the virus to evolve further.
Not so great news this morning from Israel. The MoH reports that the effectiveness of Pfizer to protect against contracting Delta drops to 64% from 94% against other strains.
This have major implications for herd immunity & the ability of the virus to further evolve. #UpdateNow— Yaniv Erlich (@erlichya) July 5, 2021
The new data: efficacy against severe disease confirmed
The data released in May showed aefficacy of the Pfizer vaccine equal to 94.3% in the prevention of asymptomatic infections while in June, when the Delta variant became more widespread (currently causing 90% of infections in Israel) the coverage would be around 64%. However, these are preliminary data and, more importantly, the vaccine proved highly effective against severe disease which can lead to hospitalization or death. Israeli experts note that compared to serious disease the efficacy rate down by only 5%: in May, the vaccine efficacy rate in preventing hospitalizations was 98.2%, while in June of 93%.
The other studies
Other studies have instead confirmed that vaccines also work well against the Delta variant, as long as the vaccination cycle is complete. Against the Delta variant, the protection for Pfizer and Moderna vaccines drops from 90-95% to 85-90%, which means that 10-15% of those fully vaccinated can be infected. For AstraZeneca from a level of 70-75%, it drops to 65-70%. With just one dose against the Delta there is a collapse: with Pfizer you reach just 30% effectiveness and with AstraZeneca at 20%. Therefore, 70-80% of people can be infected (two weeks after the injection, because first the organism is still a virgin from an immunological point of view). It has been seen in both Israel and the UK that vaccinated people rarely get worse if they get Covid. In the UK, despite Delta’s dominance out of 20-25 thousand infections there are on average 15-20 deaths and few hospitalizations in intensive care units. People can then become infected, but the mortality and stress on ICU admissions drop to the levels of a flu.
No hospital congestion
Today Israel represents one of the countries in the world with the highest percentage of immunization of the population against Covid-19, with the 57% of citizens who completed the vaccination cycle, 88% of which belong to the age group over 50 years. According to information released by Israel 51% of new infections among people already vaccinated, while the other half of the new infections would concern children not yet immunized. Most new cases asymptomatic or mildly symptomatic. The positivity rate was around 0,7% and over the last week the number of positives doubled from 1,228 to 2,597. On Sunday, out of 37,000 tests carried out, 292 people tested positive and hospitals were treating 63 patients with complications, 34 in serious conditions, of which 16 with ventilators. The computational biologist Eran Segal Israel’s Weizmann Institute of Science said the country is unlikely to experience the high levels of hospitalizations seen earlier this year as there were far fewer critically ill patients. From the new data we learn that the vaccine is effective in preventing severe disease and therefore the danger of congestion of distant hospitals. To reach a record of hospitalizations as in the period before the introduction of the vaccine, we should have 15-20,000 infections per day.
July 6, 2021 (change July 6, 2021 | 13:01)
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