Mixing vaccines

A STUDY by the Indian Council of Medical Research (ICMR), released on Sunday, has shown that giving people a shot of Covishield, followed by Covaxin as the second dose, is safe and improves immunity. The apex medical body has stated that such a mixed regimen will help to ‘overcome the challenges of the shortfall of particular vaccines, and remove hesitancy’, especially in settings where multiple Covid-19 vaccines are being used. However, the ICMR has hastened to add that a multicentre randomised control trial needs to be carried out to conclusively prove these findings. The study has come out days after Minister of State for Health Bharati Pravin Pawar, in a written reply in the Rajya Sabha, said that no recommendation to mix the first and second doses of Covid vaccines had been made by the National Technical Advisory Group on Immunisation or the National Expert Group on Vaccine Administration for Covid-19.

Though India has administered over 50 crore doses so far, supply delays and vaccine hesitancy have impeded efforts to expedite the vaccination programme. Mixing of vaccines can give a fillip to the campaign, subject to validation of the ICMR study at the international level. Several countries, including Russia, Germany, South Korea and Thailand, are keen on switching to different vaccines for second doses or booster shots, even though the World Health Organisation (WHO) had said on July 12 that the practice of mixing vaccines was a ‘dangerous trend’ since there was little data on record about its health impact. Europe’s drug regulator, too, has not made any definitive recommendation on combining shots.

The ICMR study won’t be enough to dispel doubts in the people’s minds as long as the WHO keeps sounding a cautionary note. The findings must be reconciled with scientific evidence available with the global health body. With research to establish the safety or otherwise of mixing vaccines continuing, it is not advisable to jump to conclusions. The government should take an informed decision on the matter, once it has sufficient data to reassure the public.