Jun 18, 2021

Mawazo Writing Africa

Writing about the main

Experts differ on vaccinating people with past Covid-19 infection

While a study by the Cleveland Clinic in the United States suggests that there is no point of vaccinating with a history of the disease, Kenyan scientists and other studies offer contrary advice.

The study evaluated the effectiveness of Covid-19 vaccination among individuals with or without a history of severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) infection.

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It revealed that subjects with previous Sars-CoV-2 infection do not get additional benefits from vaccination.

The study, which is yet to be peer-reviewed, suggested that Covid-19 vaccines should be prioritised for individuals without prior infection.

Conducted on 52,238 employees of the Cleveland Clinic, participants received two doses of the Pfizer/BioNTech or Moderna vaccine at an interval of 28 days.

Second dose important

A participant was considered vaccinated after 14 days of receiving the second vaccine dose. Similarly, a subject who tested positive for Covid-19 at least 42 days before the vaccination started was considered previously infected.

Of all enrolled participants, five per cent had previously been infected while 59 per cent were not. About 63 per cent of all vaccinated subjects received the Moderna vaccine.

“Of all infections during the study period, 99.3 per cent occurred in participants who were not infected previously and remained unvaccinated,” the study says.

“In contrast, only 0.7 per cent of infections occurred in participants who were not previously infected but were currently vaccinated.”

“Importantly, not a single incidence of Covid-19 infection was observed in previously infected participants with or without vaccination,” it states.

“There was no significant difference in Covid-19 incidence observed between previously infected and currently unvaccinated participants, previously infected and currently vaccinated participants, and previously uninfected and currently vaccinated participants,” concludes the study.

Boosting immunity

However, the reality of the situation is complex, and other experts and recent research have shown previously infected people still can benefit from getting the vaccine.

But, according to Health Director-General Dr Patrick Amoth, it is necessary to get a vaccine regardless of whether you had been infected before or not.

“What we still don’t know is how long it takes for an individual who had been infected before and recovered from Covid-19 to have natural immunity, so they still need the vaccine to boost immunity,” he said.

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Prof Matilu Mwau, an infectious-diseases expert and a deputy director at the Kenya Medical Research Institute, said the only time one can prove to have immunity and safety is after getting vaccinated.

“We have been vaccinating children against several diseases even after they are infected. The only time one can prove to be safe is after getting vaccinated. We are better with a shot in our arms than none,” he said.

The World Health Organization says people who have been infected should get vaccinated against the coronavirus anyway, unless their healthcare provider tells them otherwise.

“Even if you have had a previous infection, the vaccine acts as a booster that strengthens the immune response,” WHO says on its website.

The US Centers for Disease Control and Prevention says “experts do not yet know how long you are protected from getting sick again after recovering from Covid-19”.

Checking for past infection

Dr Ahmed Kalebi, a consultant pathologist and the president of the International Academy of Pathology in East Africa, on the other hand, advises the Ministry of health to consider conducting a serological test at the point of administering the first dose of the vaccine to determine those with past infection.

He said that for those who have been previously infected, there is no need of giving them a second dose and that one dose can give them adequate immunity.

“There is no point in giving people who have had prior Covid-19 two doses of the vaccine when only one dose provided can offer adequate immunity,” he said.

“All we need to do is conduct free serological testing prior to vaccination to save many doses and allow vaccine redistribution globally.”

Meanwhile, a study released in April by the Penn Institute of Immunology also shows that people who had “recovered from Covid-19 had a robust antibody response” after getting just one dose of the two-dose coronavirus vaccines.

“The findings suggest that only a single vaccine dose in individuals recovered from Covid-19 may be enough to induce a maximal immune response,” a news release said.

“This is likely due to a primary immune response because of their natural infection.”

The possibility of using a one-dose vaccine regimen for previously infected people is still being examined.

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