Noida: A booster dose of a Covid-19 vaccine could help protect the elderly and the vulnerable from the highly transmissible Omicron variant of SARS-CoV-2, the virus that causes Covid-19. But experts caution against booster doses for all, as India is yet to provide the first dose of Covid-19 vaccine to 10% of the adult population, and the second dose to 36%.

On December 25, Prime Minister Narendra Modi announced that fully immunised healthcare and frontline workers would be eligible for a third, booster dose of Covid-19 vaccine, as would those above 60 years who have comorbidities, starting January 10. Children in the age group of 15-17 years will also be eligible for vaccination against Covid-19, the PM said starting January 3. Covid-19 cases in India have doubled from about 6,300 on December 27 to over 13,000 on December 29.

The announcement makes 74 million children eligible for a vaccine, in addition to the 939 million adults already eligible. A booster dose to frontline workers and health workers would mean 30 million additional doses. Another 137 million doses would be required to give a precautionary dose to those over 60 who are advised a third dose by their doctors.


"Based on what other countries have done, it does make sense to prioritise healthcare workers and the most vulnerable (the elderly with comorbidities), although I would have been more generous and given the vaccine to everyone with comorbidities," said Gagandeep Kang, microbiologist, virologist and professor at the Christian Medical College in Vellore.

"Booster dose would save the older population who are the most vulnerable from severe forms of the disease…The only negative would be that some adults in India are yet to receive the first two doses. The booster programme would divert the resources," said Ambrish Dutta, an epidemiologist at the Public Health Foundation of India.

Children, on the other hand, do not need to be prioritised for vaccines as there is little evidence of severe disease in children, except children with comorbidities, experts said.

Several developed countries including the UK, the US and Israel have been providing booster doses of the Covid-19 vaccine since July 2021. As of December 27, at least 97 countries were giving booster doses, according to Our World in Data.

The World Health Organization recommended an additional dose of a Covid-19 vaccine for the immunocompromised on October 26, 2021. However, it cautioned against a blanket booster dose for all before all eligible adults are double-vaccinated, and called for an evidence-based approach to ration vaccines while minimising death and severe illness.

Limited data on vaccine effectiveness in India, global evidence supports booster doses

Protection against symptomatic infection from different variants might reduce by up to 50% within a year of getting the vaccination, according to this analysis of studies on protection by vaccines against the Alpha, Beta and Delta variants of Covid-19.

Preliminary data shows that infection-induced and vaccine-induced immunity may not sufficiently block the spread of Omicron, noted the Indian SARS-CoV-2 Genomics Consortium (INSACOG) in November 2021. Similarly, vaccine immunity fell over time and was lower against the Omicron variant than against the Delta variant, said the UK Health Service Authority. There is no data on the effectiveness of Covaxin yet.

Two doses of the Oxford-AstraZeneca vaccine (branded CoviShield in India) offered little to no protection against the Omicron variant, according to this December 14 preprint from England. The Omicron variant was not neutralised by antibodies in six of 12 vaccinated and previously infected people who received the Pfizer vaccine in South Africa, found a pre-print by the South African Centre for Epidemic Response and Innovation.

Omicron can also evade immunity from previous Covid-19 infection, which was not the case with the earlier Alpha and Delta variants of the virus, according to a study from South Africa which found 35,670 suspected reinfections among nearly 2.8 million with Covid-19 until November 27, 2021.

This could be because of the differences between the variants and the ancestral strain of the virus, according to Shahid Jameel, a virologist at the Wellcome Trust/DBT India Alliance, an independent organisation that funds research in public health. "Existing vaccines are based on the original virus, and the Omicron spike gene has many changes," Jameel told IndiaSpend. "Antibodies raised by vaccination show about a 40-fold drop in neutralisation titers (the concentration of antibodies against the virus in a serum sample) against Omicron."

"We cannot expect vaccines to protect against infections, but they do protect against severe illness and death," Kang said. "Unfortunately, we have limited data on the effectiveness of vaccines from right after the vaccine was rolled out, so we cannot say if the vaccines protect against disease six to nine months later."

"Studies do support that a booster dose would increase the effectiveness of vaccines to avoid severe disease and death," said Dutta.

Booster doses do more than just increase the number of antibodies, according to experts. "Antibody titers will increase, antibodies will mature and become better at neutralising variants, while cellular immunity and immune memory will also improve," said Swapneil Parikh, a doctor and author of The Coronavirus: What You Need to Know about the Global Pandemic. "All in all, protection against severe disease due to Omicron and other variants will improve, and I think it will be more durable, but only time will tell."

"But we have no evidence of vaccine immune response waning (thus necessitating a 'booster' dose)," because just evidence of a reduction of antibodies does not mean that the body cannot produce an immune response to the virus," said Kang, adding that she liked that India called it a "precautionary" dose, rather than a booster.

On December 22, 2021, the strategic advisory group of experts of the WHO recommended that the immunocompromised be given three doses instead of two within one to three months of the second dose, as part of the primary vaccination drive. The research on which the recommendation was based did not include inactivated virus vaccines such as Covaxin, one of the vaccines used in India.

There will be a report on the effectiveness of Indian vaccines against the Omicron variant soon, Health Minister Mansukh Mandaviya told the Rajya Sabha on December 20.

Additional dose announced before India met the deadline for full vaccination

On May 13, the Union Health Ministry had said that India would have 2.16 billion vaccines available by December 31, enough to fully vaccinate its eligible adult population with the Covid-19 vaccine. But as of December 30, with 1.44 billion doses administered between January 16 and December 29, only 64% of the population has been fully vaccinated.

At the current pace (between December 23 and December 29) of 5.8 million doses a day, India will need almost four months to fully vaccinate the adult population, until March 14, 2022, according to our calculations based on data available from the CoWIN dashboard. For the currently announced booster programme and child vaccinations, along with fully vaccinating the adult population, India would need 107 days or until April 14, 2022. With boosters for those above 60 years, it would take another 24 days, until May 9, 2022.

If boosters are given to all adults, it would take 262 additional days, meaning that all adults will be vaccinated with three doses by September 2022 at the current rate of vaccination, our calculations show.

The overall rate of vaccination also hides vaccine inequities between states, as also between rural and urban populations, between men and women, and between the general population and scheduled tribes. Booster doses could mean that it will take longer for all adults to get two doses of the vaccine.

"No country can boost its way out of the pandemic," WHO director general Tedros Adhanom Ghebreyusus said during a press conference in Geneva. After the emergence of Omicron, the WHO decried "persistent vaccine inequity" a year into the global Covid-19 vaccination effort, and said the "horrific inequity" contributed to the emergence of new variants like Omicron.

Further, vaccines can be updated to protect against newer variants of the disease, but making them available to the people is the challenge, according to Jameel. "Manufacturing sufficient quantities to vaccinate populations is the challenge and takes time. Indians will need to complete a two-dose schedule with available vaccines and booster shots," he added.

"India makes enough doses to give a second dose to all adults, give a third dose to everyone aged above 60 years, to vulnerable people below 60 years and to healthcare and frontline workers, while also contributing hundreds of millions of doses to the global vaccine supply," said Parikh.

India produces nearly 250-275 million doses of Covishield in a month and 50-60 million doses of Covaxin in a month, Minister of State for Health Bharati Pravin Pawar told the Rajya Sabha on December 14, 2021. Over 1.52 billion additional doses that would be required to give three doses to all eligible adults, could be produced by April 2022 at the current rate of production.

Two new vaccines--Corbevax, which will be available in India in February 2022, and Covovax--were also approved by the WHO for emergency use.

Booster dose for the vulnerable, focus on full vaccination

"We should maximise two-dose coverage, but a large number of people do need the third dose," said Parikh. "Not every dose administered will reduce the risk of severe outcomes by the same amount. A third dose for an 85-year-old individual or an immune-compromised individual may reduce their risk of death due to Covid-19 by a greater amount than a second dose for an 18-year-old who has already had Covid-19," explained Parikh.

However, vaccinating the adult population should be a priority, added Dr Parikh. "Vaccine equality is a must. Primary vaccination will save lives and may reduce the risk of variant emergence and boosters would be beneficial to reduce risk of severe outcomes in vulnerable or highly exposed groups," he said.

"In a gradual manner, all age groups should be included in the booster program. First phase, 60+ population and then 45+ and so on," said Dutta.

Do children need the vaccine?

More than half the children aged 6-17 years had antibodies for Covid-19 in July 2021 after the second wave, found the government's fourth seroprevalence survey. Experts point to the low levels of severe illness and death among children to argue that healthy children do not need to be prioritised for vaccines yet.

"We don't know what percentage of the deaths and severe illness occurred in healthy children," said Kang. "But there was no pressure on paediatric ICUs and children, showing that kids can handle the virus.

"But we cannot wait for the entire population to be fully vaccinated before we start giving boosters and open the vaccine for children," she said. "A 60% cutoff for full vaccination is good enough to include more people in the vaccination eligible list."

(Nileena Suresh and Ananya Singh contributed to this story.)

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