COVID-19: What is known about the combination of Pfizer with the vaccines from Sinopharm, J&J and AstraZeneca?

Various countries in the world have resorted to the combination of vaccines due to the growing evidence that the protective effect against the COVID-19 it is higher, also due to the availability of vaccines: some manufacturers have delays in delivering their batches and governments were forced to apply a different dose.

Recent studies have shown that applying one dose of one vaccine and placing a second dose of a different technology

Pfizer and AstraZeneca

Injecting a vaccine against, and spacing the two doses of the latter several months apart, substantially improves immunity, according to two studies published in June by the University of Oxford.

The researchers also ensure that the vaccine after the second and third doses than after the first ”.

In a separate study also published that month, the University of Oxford also found that combining doses of AstraZeneca / Oxford and its German-American competitor Pfizer / BioNTech, injected four weeks apart, also improves the immune response against COVID-19. .

Efficacy varies, however, according to the order, according to this study that found that one dose of AstraZeneca / Oxford followed by another of Pfizer / BioNTech generates a “better immune response” than the other way around.

Results for a 12-week interval between the two doses will be available shortly and “will be instrumental in deciding the future of the UK vaccination program ”, said Professor Jonathan Van-Tam, England’s deputy chief medical officer.

More time between doses

The researchers showed that, far from diminishing the effectiveness of the vaccine, AstraZeneca / Oxford needed improves the immune response to the virus.

“This should be reassuring news for countries with fewer vaccine supplies, which may be concerned about delays in obtaining second doses.”, then commented Professor Andrew Pollard, director of the Oxford Vaccine Group, which developed the vaccine together with the Anglo-Swedish pharmaceutical group AstraZeneca.

“There is an excellent response to the second doseI know of having received the first one ”, stressed.

Another study from the same university published in February by the prestigious scientific journal in The Lancet already indicated that the efficacy of the vaccine was greater with a three-month interval between doses (81%) than with a six-week interval (55%). ).

As a result of this new research, the scientists also discovered that a third dose injected more than six months after the second leads to an immune response against COVID-19, including against known variants of the coronavirus.

Lower risk of infection

Another study from the University of Umea (Sweden) published this month found that people who received a first dose of COVID-19 vaccine from Oxford / AstraZeneca and a second dose of mRNA had a lower risk of infection compared to those who received both doses of the first preparation.

In messenger RNA (mRNA) vaccines, such as those from Pfizer-BioNTech and Moderna, ribonucleic acid is used to develop an immune response. The professor of geriatric medicine at the aforementioned university, Peter Nordström, who has carried out the research,

“However, our study shows a greater risk reduction for people who received an mRNA vaccine after receiving a first dose of a vector-based vaccine, for both doses “added the specialist, whose study has been published in the journal Lancet Regional Health.

When the use of the Oxford-AstraZeneca vector-based vaccine was stopped for people under 65 years of age, all people who had already received their first dose of this preparation were recommended one of mRNA as a second dose. During an average follow-up period of more than two months after the second dose, the study for the combination of Oxford-AstraZeneca and Pfizer-BioNTech, and a 79% lower risk for Oxford / AstraZeneca and Moderna, both compared to the unvaccinated individuals.

For people who received two doses of the Oxford-AstraZeneca vaccine, the risk reduction was 50%. These risk estimates were observed after accounting for differences regarding vaccination date, participant age, socioeconomic status, and other COVID-19 risk factors.

The investigators have pointed out that the efficacy estimates were applied relative to, which dominated the cases during the follow-up period. Previous research has shown that combined vaccination programs elicit a robust immune response, but it is not clear to what extent these schedules can reduce the risk of clinical infection, according to the analysis.

The Umea study, which analyzed the cases of 700,000 people, is based on data from national registries from the Swedish Public Health Agency, the Swedish National Board of Health and Welfare and Statistics. The study results may have implications for vaccination strategies in different countries, according to experts.

Pfizer y Johnson & Johnson

A preliminary study – sponsored by the United States Government on the effects of mixing different vaccines as booster doses – conducted this month this week showed that people who have received the J&J messenger RNA (mRNA) vaccine, such as those from Pfizer or Modern

The results published on the preprint portal medRxiv show that the combination of COVID-19 vaccines produces as many or more antibodies than using the same vaccine as a booster, and there were no safety problems.

J & J’s single-shot vaccine was never as effective as its double-dose mRNA counterparts, but some evidence suggests that, due to the viral vector technology behind it.

However, the company presented data showing that efficacy against symptomatic covid increased from 70% to 94% in a trial conducted in the United States after a second dose given two months after the first. These figures are similar to those associated with mRNA vaccines.

Based on these data, a panel of high-level US medical experts unanimously approved recommending authorization for a second injection of Johnson & Johnson (J&J) vaccine.

Pfizer y Sinopharm

Regarding the combination of vaccines, the studies focus mainly on the mixture of vaccines used in the US and Europe (AstraZeneca, Moderna, Pfizer, J&J), so the

A few days ago, the World Health Organization’s Strategic Advisory Expert Group (SAGE) on immunization recommended the booster for people at risk, such as older adults and personnel in high exposure. But he also spoke about the Chinese inactivated virus vaccines Sinopharm and Sinovac: either the same brand or different.

“For the elderly who received Sinovac and Sinopharm, the third dose needs to be given, it can be of the same vaccine that was used or if the country has more availability, others can be used. It was very well established that this vaccination can include different vaccines, and can be adapted to the situation of each country ”, details the deputy director of the Pan American Health Organization, Jarbas Barbosa.

, which uses inactivated virus technology, are getting a boost from Pfizer. The Ministry of Health stated that there was scientific evidence indicating that receiving doses of different technology (inactivated / mRNA) enhances protection.

A recent study released by the Government of Chile, one of the first studies on the effectiveness of an additional injection in inactivated virus vaccines, showed that it reduces the risk of hospitalization by up to 96%.

The research, which considered a total sample of 11.2 million people, analyzed the effectiveness of administering a third dose in 2 million people who had completed their immunization schedule with the Chinese Coronavac, from the Sinovac laboratory, the majority in the country .

Two weeks after a third injection, which was shown on average by those who only got two doses, according to the research.

With respect to hospitalizations, the third dose of AstraZeneca reduces its probability by 96%, that of Pfizer by 87% and that of Sinovac by 88%, compared to 84% protection of those who did not receive it.

Pfizer y Sputnik V

The combination of Sputnik V and Moderna or Pfizer vaccines “is effective and safe,” according to a study by the National Autonomous University of Honduras (Unah), released this Tuesday, with the advice of renowned Honduran scientist Salvador Moncada, who resides in London.

“Preliminary immunogenicity results show an immune response equal to or greater than what s”, indicated the Unah through its newspaper Presencia Universitaria.

He added that the increase in antibodies between the first and second doses was significant in the vaccinated participants, with laboratory evidence of natural infection by SARS-CoV-2, and that “They presented a considerably higher immune response than those who had not been infected”.

According to the report, Unah led the study due to the need to find a solution to the lack of provision of the second dose of the Sputnik V vaccine, which will be applied to 40,000 Hondurans who were awaiting the arrival of the second component.

“After 14 days there was a and at 21 a reduction of this response was observed, although it was always persistent and higher compared to day zero ”, the study notes.

Agencies

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