Despite the warning from the WHO against mixing and matching Covid-19 vaccines, Bhutan has decided to go ahead with the mix-matching mode of vaccination for the second dose. The immunization drive will begin on 20 July to administer second doses of the Covid-19 vaccines. 

The National Immunization Technical Advisory Group (NI-TAG) has recommended that a person who had received the 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.

In the wake of the fast-spreading Delta variant, Dr. Sonam Wangchuk, the head of the body, said that a heterologous regime (mixing of vaccines) of vaccination was found to be more effective and safe. The clinical trials, he said, were found safe and effective in many western countries.

“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 was quoted as saying by Kuensel.

Earlier, there were concerns after the World Health Organisation’s (WHO) chief scientist, Soumya Swaminathan advised against mixing and matching Covid-19 vaccines from different manufacturers, termed it a “dangerous trend”. She said there was limited data on the method to suggest if it is safe.