Single-dose Kovid vaccine strategy may be risky, researchers say – Health

Imagem Assine o Estadão

SAO Paulo – Adopt a new immunization strategy in Brazil from the United Kingdom that may face more challenges than solutions Estadão. European country, which decided to postpone second dose of vaccine Coronavirus For the 12 weeks following the first injection, it is not only different from our reality, but it is several steps ahead in the fight against the epidemic.

The measure adopted by the United Kingdom, developed by Pfizer / BioNTech and the University of Oxford / Astrazeneca, extends the original interval of 21 days between two vaccine applications from Kovid-19 to 12 weeks. It aims to increase the number of immunized people in the country and curb the transmission of the disease, which is crowded with ICU and now facing the spread of new strain of virus (B.1.1.7). Also on Monday, 4, Prime Minister Boris Johnson decided the official lockout due to the high number of deaths and hospitals in the country.

“In the UK there have always been initiatives in terms of vaccination compared to other countries and in general, they are doing very well. It was a bold decision, to take risks ”, evaluates Rosanna Richtmann, advisor to the Immunization Committee of the Brazilian Society of Infectious Diseases. For her, the biggest proponent is that this new strategy will guarantee more people to be vaccinated in less time, while the main offensive factor is the lack of technical data and scientific basis for it.

So far, Germany, Belgium and Denmark have already announced that they are studying to follow the example of the United Kingdom and increase the interval between doses, mainly with the slow pace that led to vaccination in these countries Has been upgraded. In Brazil, however, experts say this strategy may not be the most appropriate.

“In general, the strategy is acceptable, but it depends on each country’s health system. Higher than average speed in England. This does not mean that it will work in all countries. Brazil is a very large country, so with additional challenges, such as a vulnerable population that is large ”, explains Elisu Waldman, professor in the Department of Public Health Epidemiology at the University of Sao Paulo (USP).

“Of the two vaccines they propose, only the Oxford vaccine proved to be more immunogenic (develops more antibodies) when the interval between doses was longer. For this, it is not a bad idea, as it can produce a better immune response. We still have no information about Pfizer telling Roshan. Official data indicated that the Oxford / AstraZeneca immunizer, which will be produced in Brazil by Fiocruz, guarantees an overall effectiveness of 52.4% after the first dose, above the minimum threshold set by the World Health Organization (WHO).

Service Estadão, Doctor Lily Yin Wex, coordinator of the Special Immunobiology Reference Center at Unifox and responsible for coordinating the clinical study of the vaccine developed by Oxford / Estrazeneca in Brazil, Said last week After that first dose the antidote already “begins to protect”. She views the British approach as possible in Brazil and says that the measure “reaches as many people as possible to make an impact in this very terrible situation”.

For Natalia Pastrnak, a PhD in Microbiology from the USP and President of the Instituto Questo de Siocesia (IQC), the decision is more in the field of management and logistics than in medicine or scientist. “There is no simple answer. Vaccines have been tested for a given dose regime and changing it is always a risk, as there is no scientific data to predict what will happen. When it is specified and management To improve and vaccinate more people, that gap changes, so it’s a public health decision. ”

On extending the period between applications, Rosna also warned of a low level of withdrawal of Brazil’s population to another level. “When you spread this interval over three months, it is more complicated to follow. He adds that the second dose greatly reduces coverage.

“Our concern is still a step backwards, because we need to know what doses we will have, which are the vaccines and when they will be applied. We do not have that either ”, says Natalia. The Ministry of Health has not yet set a date for starting vaccination, but 20 January can be seen as the most optimistic scenario. The São Paulo government hopes to launch the campaign on January 25, but Coronavac is an immunizer developed by the Chinese laboratory Synovac and the Butanta Institute, which has not yet released its efficacy data nor from the National Health Monitoring Agency (Envisa) Has received approval. “For them, in the UK as well as for us, this is an emergency.”

According to the report, the Oswaldo Cruz Foundation (FiroCruz), responsible for the production of the Oxford / Estrázeneca vaccine in Brazil, stated that whichever dosage regime it determines is responsible for the national immunization scheme, which is up to the Ministry of Health.

In a note, Folder said that technical questions about the development are for pharmaceutical companies, but said the national plan for vaccination against coronavirus is “dynamic and will be adapted – if necessary – as we have vaccines.” Approved and included in SUS. “.

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