Bhutan to go ahead with mix and match vaccines

The National Immunization Technical Advisory Group (NI-TAG) has recommended that if Bhutanese who had received Covishield (AstraZeneca) vaccine for their first dose, a booster dose of an mRNA vaccine (Pfizer or Moderna) produced a stronger immune response (immunogenicity) against the SARS-CoV-2 virus.

NI-TAG member, Dr Sonam Wangchuk, said that in the wake of the fast-spreading Delta variant of the SARS-CoV-2 virus, heterologous regime (mixing of vaccines)  of vaccination was found to be more effective.

He said that clinical trials and studies conducted in developed countries have shown that mixing of vaccines was not only effective against the emerging variants of concerns but it was also safe.

“Technically, there is no issue of mixing vaccines and this is not being done for the first time. Heterologous prime-boost approach of vaccination is a common practice in other vaccines like malaria, TB, some cancer therapy, and Ebola vaccines,” he said.

As per emerging evidence, Dr Sonam Wangchuk said that mixing two different Covid-19 vaccines resulted in minimal side effects. “The side effects were similar to that during the first dose of Covishield vaccine such as headache, fever, joint pain, and pain at the site of injection.”

He explained that any vaccine or any medicine came with a certain level of side effect and that it was ‘absolutely normal’. “Even a paracetamol triggers some side effects,” he said, adding that given the uncertainties in the region and the huge population, the possibility of having new variants of concern was very likely.

“Studies show that having the same vaccines for two doses against the Delta variant of the virus reduced the efficacy to about 40 percent for AstraZeneca vaccine. On the other hand, if you mix and get mRNA vaccine for your second dose, the efficacy was over 80 percent,” Dr Sonam Wangchuk added.

There were concerns among some Bhutanese after the World Health Organisation’s (WHO) chief scientist, Soumya Swaminathan  advised against mixing and matching Covid-19 vaccines from different manufacturers, calling it a “dangerous trend”.

The scientist was quoted saying that there was limited data on the mix-and-match approach to Covid-19 vaccination by the news agency Reuters. “Maybe it will be a very good approach but at the moment we only have data on the Oxford-AstraZeneca vaccine followed by Pfizer,” she said.

However, what many missed out was that her comments stemmed from individuals deciding to mix vaccines or take additional doses on their own without public health guidance.

Soumya Swaminathan tweeted saying: “Individuals should not decide for themselves, public health agencies can, based on available data. Data from mix and match studies of different vaccines are awaited – immunogenicity and safety both need to be evaluated.”

Science-based decision

Sowai Lyonpo (health minister) Dechen Wangmo said that what the government decides will be based on science and evidence. “The evidence on mix-and-match is very strong for now and NI-TAG also recommends it.”

Lyonpo said that many were also of the belief that the government was opting for the mix-and-match approach due the shortage of vaccines. “This is not the case. Our reason for going ahead with this plan is purely based on the efficacy of the vaccine.”

Lyonpo explained that vaccination was an individual choice and strictly voluntary. “We are happy to provide our people with a choice of vaccine.” However, she said that keeping the vaccine choice open to individuals would also invite logistical challenges.

“If a person registers to take vaccine A and then at the last moment decides to go for vaccine B, it would be difficult for us to cater to many such decisions,” Lyonpo said.

Kuensel learnt that the NI-TAG has recommended homologous and heterologous methods to individuals based on their age. It was learnt that those between the age of 18-34 were recommended Moderna vaccine for their second dose, while those above 35 years to be vaccinated with AstraZeneca vaccine.

Lyonpo said that the government would decide on this and share the details in a day or two.

Provisions to vaccinate children below 17 years old are also being considered this time.

Meanwhile, the minister urged all the eligible people to get vaccinated in order to achieve the required coverage for herd immunity. “Unless we achieve herd immunity, the existing protocols will remain. We cannot imagine relaxing our protocols until we get a certain level of assurance through the vaccine coverage,” she said. “If the virus can bring countries like the US to its knees, we stand no chance. Our health system is not as advanced as other countries.”