the effectiveness of vaccines remains high against Delta-

of Laura Cuppini

The “New England Journal of Medicine” on AstraZeneca and Pfizer: good with two doses (with slightly lower numbers than Alpha), with one the coverage drops to 30%

How can we fight the Delta variant?
The double dose of AstraZeneca and Pfizer / BioNTech vaccines protects against the strain that is spreading rapidly around the world (B.1.617.2). This is confirmed by an important English study, published in the New England Journal of Medicine. The PHE, the public health body, has analyzed 20 thousand patients with Delta variant (formerly Indian). Two doses of Pfizer vaccine were found to be 88% effective in preventing symptomatic disease, compared with 93.7% against Alfa (formerly English). AstraZeneca was 67% with two doses, compared to 74.5% for Alfa. In other words, the double injection works a little less against the new variant, but still represents a very important barrier against more severe forms, including hospitalizations and deaths. The study gives another key information: for both vaccines the effectiveness of immunization with a single dose stops at 30%, compared to 48.7% measured with Alpha. A confirmation of the need to complete the vaccination cycle while protecting as many people as possible. Good news also for Johnson & Johnson’s single-dose: the immune response lasts at least 8 months and also generates neutralizing antibodies against the Delta variant.

Do vaccines also block the circulation of the virus?
It is not yet clear how much they can stop asymptomatic forms: according to an analysis conducted in Israel, Pfizer’s efficacy against Delta would drop to 64% for symptom-free infections. So the virus is spreading, but with a small number of serious cases and deaths compared to previous months. “For some time, for reasons related to dose shortages and especially in Great Britain, priority was given to providing partial immunization, lengthening the interval between the first dose and the booster, but it was never questioned that to have complete protection it is necessary to receive both doses ”, he clarifies Giuseppe Ippolito, scientific director of the National Institute of Infectious Diseases “Lazzaro Spallanzani” in Rome and member of the technical-scientific committee.

Are the healed protected with a single dose?
The Ministry of Health has established, with a circular, that those who have overcome the disease can receive a single dose of vaccine within 12 months of recovery, also for the purposes of the green pass. “There are now multiple evidences that the immune response to the first dose in the recovered is the same or even higher to that which is obtained in individuals vaccinated with two doses but who have not previously fallen ill », explains Ippolito.

Will it be possible to achieve herd immunity?
The scientific community believes that reaching the goal of80% of the population vaccinated with two doses – in Italy it is assumed between September and October – it would drastically slow down the advance of the virus. «Even if we imagine that it continues to circulate, we will have created an immunization substrate with vaccines and natural infections that will allow us to keep it under control – says Ippolito -. We must insist on a simple fact: those who have completed the vaccination cycle are twenty times less likely to end up in hospital for Covid than those who are not vaccinated. And the Delta variant is extremely more contagious than previous strains ». There is no time to waste: in our country over 2 million over 60s are still not protected.

July 23, 2021 (change July 23, 2021 | 07:18)


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