Certain drugs can affect the efficacy of Sinovac's Covid-19 vaccine


Certain medications used to treat autoimmune rheumatic diseases like rheumatoid arthritis, lessen the protection provided by the Sinovac vaccine against Covid-19. — Filepic

Researchers at the University of São Paulo’s Medical School (FM-USP) in Brazil have found that some types of medication used to treat patients with autoimmune rheumatic diseases, such as rheumatoid arthritis, can weaken the immune response to Covid-19 induced by vaccines.

The researchers set out appraise the safety and efficacy of CoronaVac (more popularly known as the Sinovac vaccine) in patients with nine types of autoimmune rheumatic disease.

CoronaVac is produced in Brazil by the Butantan Institute.

Principal investigator Dr Eloísa Bonfá said: “We observed that some drugs, such as glucocorticoids, as well as immunosuppressants such as methotrexate and mycophenolate mofetyl, and some biologics, weaken the immune response in these patients.

“Based on this observation, we began studying different vaccination strategies, including the suspension of medication with mofetyl one week before administering the vaccine, and with methotrexate two weeks before.”

The patient’s treatments are then resumed after vaccination is completed.

According to the clinical director of FM-USP’s hospital, the risk of a weakened immune response to vaccines is high in immunosuppressed patients, as well as those with autoimmune diseases.

The former include cancer patients, patients with transplanted organs and HIV (human immunodeficiency virus) patients.

In addition, rheumatic autoimmune disease can increase the probability of thrombosis.

To find out whether Covid-19 vaccines were safe and efficacious for these people, the researchers monitored 910 adult patients enrolled at the hospital’s rheumatology laboratory for 40 days after they were given the second dose of CoronaVac.

“The patients are followed up at a tertiary centre; (including those) with severe rheumatoid arthritis and psoriatic arthritis, as well as axial spondyloarthritis, and other systemic autoimmune rheumatic diseases such as lupus, vasculitis, Sjögren’s syndrome, systemic sclerosis, idiopathic inflammatory myopathy and anti-phospholipid syndrome,” Dr Bonfá explained.

Blood samples taken to detect antibodies against the SARS-CoV-2 virus were analysed before vaccination, and 28 days and six weeks respectively after administration of both doses of CoronaVac.

The results were compared with those of a control group comprising 182 people who did not have autoimmune disease and were not taking immunosuppressants.

The results of the analyses showed that vaccination induced seroconversion to IgG antibodies in 70.4% of the patients with autoimmune rheumatic disease, compared to 95.5% of the control group.

“We saw a reduction of the immune response in these patients compared to the control group, but we considered the reduction moderate and in line with the standards set by the WHO (World Health Organization),” she said.

“A serological response at 70.4% is very important for immunosuppressed patients or patients who take medications that reduce their immunity.”

Ten days after taking the first dose, when the response to the vaccine was not complete, 33 participants in the study had Covid-19.

After 40 days, when the second dose had been administered and the response was complete, only six patients had the disease.

Four required hospitalisation.

There were no deaths.

The reduction in cases of infection among the participants, from 33 to only six, contrasted with the trajectory of new cases in São Paulo, which rose 45% in the same period.

“The sharp fall in the number of cases 10 days after the second dose shows that the vaccine is apparently efficacious, even in this population of immunosuppressed pa- tients, who are more likely to be infected.

“This reinforces the recommendation that these patients should be vaccinated,” Dr Bonfá said.

Besides the high risk of contracting infectious disease and falling severely ill, immunosuppressed patients are also more likely to suffer from comorbidities such as high blood pressure and obesity, which are risk factors for Covid-19.

In addition, it is more difficult for immunosuppressed patients to clear the virus from their bodies, compared to healthy people, which favours the emergence of mutations resulting in viral variants.

“Prioritising this group for vaccination purposes is important not just for them, but also for the entire population, as a strategy to reduce the emergence of viral variants,” she said.

Further tests are required to find out whether the same effect occurs in patients inoculated with other Covid-19 vaccines.

The study was published in the journal Nature Medicine, and was supported by Agência Fapesp and B3 S.A., Brazil’s stock exchange. – By Elton Alisson/Agência Fapesp

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