COVID-19 vaccine combination: What studies have been done around the world and what will be done in Argentina

The combination of doses of vaccines manufactured by different producers has been carried out for the control of several infectious diseases in the past. Now, the scientific world and health authorities are evaluating through clinical trials what are the benefits of the combination of COVID-19 vaccines. In Argentina, given the delay in providing doses to complete the schedules, the possibility is also being explored. In the city of Buenos Aires, one of these studies is designed to find out when it is appropriate to exchange doses of different vaccines.

Since last year, COVID-19 vaccines have been developed around the world to reduce the risk of complications and death if a person is exposed to coronavirus infection. “The way each licensed vaccine stimulates the immune system to produce antibodies against the virus varies,” said Kate O’Brien, director of the vaccines unit at the World Health Organization. “Based on how vaccines work, we believe the combination regimens will work as well,” the official said to the agency’s question. PA.

“Vaccine combinations must have at least one assessment of safety and efficacy monitored by immunogenicity, that is, the level of antibody it elicits, and these are studies that are do it quickly, “Buenos Aires Health Minister Fernán said a few days ago. Quiros. Also considered: “If for one of the vaccines the number of second doses is not sufficient, it is safest that clinical evaluations will be made on the safety and efficacy of the different combinations and not to combine on a large scale without the ‘have tested beforehand. “

Regarding the trial organized by the city of Buenos Aires, “it is important that a study be conducted on the combination of COVID-19 vaccines in Argentina,” he commented. Infobae Dr. Liliana Vázquez, from the Argentine Society of Infectology. “This type of trial must be approved by a research ethics board. It may take a month for volunteers to be included. There would be 500 people included in each group, who can give us very important information. After applying the second dose, it is necessary to wait between two to three weeks to measure the immune response and compare it with the traditional scheme ”, said Vázquez, a doctor specializing in infectious diseases at the Suizo Maternity in Argentina and at the Finochietto Sanatorium.

One of the vaccine combination studies has been carried out at the University of Oxford since last January in England. Through the Com-Cov study, the administration of doses four weeks apart was analyzed in 850 volunteers aged 50 years and over. AstraZeneca vaccine was applied first, followed by Pfizer / BioNTech vaccine dose. This combination induced larger antibody and T lymphocyte responses than the reverse application (Pfizer / BioNTech followed by AstraZeneca). The two mixtures induced higher antibodies than two doses of AstraZeneca alone, according to the researchers.

Lead researcher Professor Matthew Snape of the University of Oxford said the results did not undermine UK public policy of giving the same vaccine twice: “We already know that the two standard treatment regimens are very effective against serious illness and hospitalization, even against the Delta variant when given eight to twelve weeks apart.”

Now they are testing the dose combination with vaccines from AstraZeneca, Moderna, Novavax and Pfizer-BioNTech in the UK. The study is called ComCov 2 and, as stated on the official website, it will recruit 1,050 participants. As new SARS-CoV-2 vaccines become available, more vaccines may be included in the trial, so the total number of participants may increase.

Study participants in England must be 50 years of age or older and have received a dose of the COVID-19 vaccine as part of the national immunization program, approximately 8 to 12 weeks before enrolling in the study. They may not have already received their booster dose. They will not know which vaccine they received for their booster (ie they will be “blind”).

In Spain, another vaccine combination study is also underway and started in March. In mid-May, the Carlos III Institute in Madrid (ISCIII) presented the preliminary results. This is the CombivacS clinical trial and it concluded that administering a second dose of Pfizer / BioNTech to those who received a dose of the University of Oxford / AstraZeneca vaccine developed neutralizing antibodies without serious side effects.

The work carried out with Spanish participants was recently published in the magazine The Lancet and shows that the combination of doses of the two types of vaccines also enhances cellular immunity. It provided evidence that the vaccine combination induces “a potent humoral and cellular response to COVID-19,” said Alberto Borobia, clinical pharmacologist at Hôpital de la Paz and one of the authors of the research.

In Germany, researchers at the University of Saarland found that people whose first injection was AstraZeneca and the second BioNTech-Pfizer had a stronger immune response. than that of patients who received two doses of the same vaccine, either AstraZeneca or BioNTech.

The results of the study in Germany are preliminary. The researchers announced on June 6 that they would study the role played by patients’ age and gender, for example, and also look at combinations that could trigger more serious side effects. Although a full evaluation of the data has not yet been completed, the team that conducted the study were surprised by the results on the benefits of the combination, said Martina Sester, professor of transplantation and immunology. infections at the University of the Saar, in a statement. Release.

Researchers at the Gamaleya Institute in Russia are also testing a combination of their Sputnik V vaccine and AstraZeneca injection. Sputnik itself is based on a mix and match approach because the first and second doses already have different formulas. The results of this study have not yet been published in a scientific journal.

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