Advisory group prefers 8-12 weeks’ interval between two shots

As uncertainty looms over when and how the country will start its immunisation programme against Covid-19, experts are pondering how to ensure a wider coverage of the population with vaccine shots.

The goal is to protect as many people as possible against the novel coronavirus, compelling experts to think of pushing back the schedule for second doses.

The National Immunisation Technical Advisory Group discussed the issue on Sunday and came up with a proposal that the interval between two shots be extended from 21 days to 8-12 weeks. It plans to submit the proposal to the health ministry at a later date.

The question that has arisen is "how long the immunity will persist after the first dose," said Be-Nazir Ahmed, a member of the committee.

"According to the World Health Organisation (WHO), the protection will be sustained for as long as six months," he said, adding that the latest recommendations are in favour of delaying second doses for 8 months.

Britain has already decided to delay second doses of the vaccines by AstraZeneca and Pfizer "as a way of more widely distributing the partial protection afforded by a single shot," said The New York Times in a recent report.

Health officials in the US, however, oppose the idea. "I would not be in favour of that," said Dr Anthony S Fauci, the nation's top infectious diseases expert.

However, as far fewer Americans were covered by the Covid vaccines than projected by 2020, many experts are debating on whether to go for maximum protection or maximum coverage.

British health officials said Oxford-AstraZeneca's vaccine was 73% effective in clinical trial participants three weeks after the first dose was administered and before the second dose was given. In cases where participants never received the second dose, their bodies showed resistance against the virus for about 12 weeks.

In a trial of the Oxford-AstraZeneca vaccine, volunteers in Britain were supposed to receive two doses of the vaccine about a month from one another. Some participants got the shots several months later but still gained protection against the contagious disease.

Bangladesh is depending highly on the Oxford-AstraZeneca vaccine manufactured by the Serum Institute of India.

The government has already drawn up an inoculation programme to cover 80% of the population in two years. It will pay $120 million in advance, half the price, to import three crore doses of the jab in the first phase.

"We are going to submit a proposal to the health ministry that initially we continue giving shots to more people from the priority list as the doses arrive," said Be-Nazir, former director, Communicable Disease Control of the Directorate General of Health Services (DGHS).

About 50 lakh doses will arrive a month. If the proposal to delay the second doses is accepted, the government will be able to provide more people with protection against the disease at a faster pace.

But that may cause a derailment in the vaccination programme, said Prof Nazrul Islam, noted virologist and former vice-chancellor of Bangabandhu Sheikh Mujib Medical University.

"We may think of giving shots a month apart or 40 days, but implementing such a plan will be challenging.

"We have to ensure proper usage of the vaccine after the opening of each box of doses; and maintaining a different schedule will only add to the complexities of the entire programme."