Herd immunity against Covid-19 may not be achieved without vaccinating children

Leading infectious diseases’ experts and vaccinologists have warned that herd immunity against the coronavirus cannot be achieved globally without vaccinating children, arguing that vaccinating the adults may prevent mortality, but the transmissibility of the virus would continue in the unvaccinated populations, especially children.

They said studies to vaccinate children are underway although these studies started very late. They made it clear that the transmission of the virus will not stop even by vaccinating 70 per cent of the adult populations globally.

“We may not be able to achieve herd immunity globally unless we vaccinate children as they are both in the numerator as well as in the denominator. We might be able to reduce mortality if don’t vaccinate children, but we will not be able to reduce transmissibility unless children are also vaccinated,” said Dr Saad B. Omer, the inaugural director of the Yale Institute for Global Health, while delivering an online talk on “Covid-19 Vaccines: From Trial to Market” on late Thursday night.

The talk was organised by local pharmaceutical firm Getz Pharma and moderated by the company’s head of Public Health and Research, Dr Wajiha Javed, who raised various queries that were in the minds of people regarding Covid-19 vaccines, their efficacy and safety, deployment issues and availability.

Dr Omer, who is also a member of the World Health Organisation’s Strategic Advisory Group of Experts (SAGE) Working Group on Covid-19 Vaccines, said now trials of various vaccines were being conducted in the children under the age of 18, but these trials should have been conducted a little earlier to ascertain if they were effective in preventing the transmissibility of the virus.

Regarding the safety and efficacy of different vaccines in elderly people, Dr Omer said most of the vaccines were safe for elderly, but different countries were making their own judgments and issuing advisories for the elderly in accordance with life expectancies in their own countries.

“Different countries are making their own judgments and issuing different advisories for elderly people, but you should keep in mind that the age of 60 in Pakistan is 80 in other countries. So the people who survive beyond 60 there is similar to people who survive 70 in other [developed] countries, so hopefully the people in the age group of 50 to 60 years would be prioritised and data would be available. But so far the safety profile of different vaccines is very good and in the US over 20 million have been vaccinated.”

He said data shows that hospitalisation and ICU admissions are nearly twice as high in pregnant women who have contracted Covid-19 as compared to non-pregnant women. So in that context, they should be offered vaccine but decision-making should be based on the circumstances as the benefits should be more as compared to the risks.

As far as immune-compromised people are concerned, it would depend on various types of vaccines, he said adding that vaccines should also be available for such people and given by looking at the cost-benefit ratio.

Responding to various queries by public expert Dr Wajiha Javed, the infectious diseases’ expert opined that people who had contracted Covid-19 should also get the vaccine jabs except those who were actively infected at the time of vaccination. People having the infection should wait at least for three months before getting vaccinated, he suggested.

He said that although people should be vaccinated with the same vaccine for the first and the second dose, if a second dose of the vaccine is not available, the second dose of any other vaccine of the same type can be given to strengthen the immune response in the individuals. He added that some countries are delaying the administration of the second dose as even WHO allows an interval upto six weeks to ensure that ample quantity of the vaccine is available to give the second dose of the vaccine.

Commenting on equitable access to Covid-19 vaccines to the people around the globe, he said vaccines should be provided free of charge to people except those who can afford it. He added that governments should continue to subsidise its production till a sizeable population is vaccinated in the world.

As far as how long a person would remain immunised after vaccination is concerned, he said, it is too early to predict but it is likely that the immune response following immunisation would last at least for a few years. He added that variants of the coronavirus could create problems in this regard.

According to the expert, 2022 would be a lot better as compared to the current year in many countries if they deployed the vaccines in a smart and equitable manner as we know that 80 percent deaths occurred in 16 per cent people. “So if you cover that 16 per cent population, it would reduce the mortality despite continuing transmissibility.”

Another Pakistani expert of infectious diseases, Dr Faisal Mehmood from the Aga Khan University Hospital, while talking to The News, said that in his opinion, Covid-19 may not be eradicated from the world like smallpox and people would have to live with it for long.

As far as vaccinating children is concerned, the AKUH expert, who is a member on a six-member expert committee on vaccines, said studies in children are ongoing and they may be vaccinated in the future.

“The transmission [of the coronavirus] will likely not stop even with 70 per cent coverage. I don’t think we will be eradicating this infection like smallpox,” Dr Mehmood said, adding that there is a possibility of vaccinating people every year due to the emergence of different variants of the SARS-CoV-2 in the future.

An official of the National Health Services, Regulations and Coordination (NHSR&C), when approached, said that currently the available vaccines are recommended for adults only, but in the coming years, it is likely that vaccines would be available for the children too.

“Preventive measures like wearing masks, social distancing and immunity development through vaccination and by natural means can result in the achievement of herd immunity to some extent, but it would be wrong to say that the virus would be eliminated completely though the current vaccines. The point is: prevent those people who have severe disease through vaccination,” said the expert said while responding to queries from The News.

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