Amidst the ongoing coronavirus pandemic, India's Drugs Controller General (DCGI) approved a proposal from the Christian Medical College (CMC) to carry out trials on the mixed use of Covishield and Covaxin vaccines.
Globally, various studies are underway to determine if a combination of two different vaccines can outperform two doses of the same vaccine. According to the World Health Organisation (WHO), there is currently limited data on the immunogenicity or efficacy of mixed vaccine doses. In India, experts are pondering whether Covishield – an adenovirus vector platform-based vaccine – can be combined with Covaxin – an inactivated whole virus vaccine.
Recently, India's apex body of biomedical research – the Council of Medical Research (ICMR) – conducted a study, which is yet to be peer-reviewed, on 18 people who were mistakenly given mixed vaccines, and found that combining doses of Covaxin and Covishield has shown better results in building immunity against the virus.
However, the study that will be conducted by CMC Vellore will be different from the one done by ICMR according to media reports. The proposed trial will involve 300 volunteers who will be jabbed with a dose each of Covaxin and Covishield.
Meanwhile, some doctors told Sputnik this move may help in curbing the vaccine shortage issue, while others said that vaccines should not be mixed "randomly."
"The most important impact of this decision is that in a poor country like India, we can use whichever vaccine is available at the time of vaccination for both the doses so that there is no delay in vaccination of the population, especially in rural and remote areas of our country. We need not wait for a particular vaccine if the supply is erratic. This will also help the distribution of vaccines by the government to at least cover second dose vaccination of the population immediately," Dr. Rajeev Boudhankar told Sputnik.
Boudhankar added that mixed vaccines will help immune-compromised patients with co-morbidities and they will no longer have to wait for a particular jab. The other advantage will be that it will help the government vaccinate the country's massive population, which in turn will help in attaining "herd immunity" faster. It will also apparently help break the chain of infections and prevent the development of mutations.
"There is no approval from the WHO or any scientific evidence as yet to suggest mixing of vaccines may provide additional benefits. However since new COVID variants are emerging, trials of different vaccines developed on similar platforms may be studied to see if it can provide a wide (different variants) and longer duration of coverage," Dr. Sunit Mediratta, a consultant neurosurgeon, told Sputnik.
Kamal Narayan, CEO of the Integrated Health and Well Being Council, told Sputnik said that the government’s decision is not unusual given the method has previously been employed to help fight HIV, Ebola, TB, and other diseases.
"The recent ICMR finding of accidental mixing of vaccines in Uttar Pradesh has kindled hope and the government’s decision to conduct a detailed study on mixing vaccines is a welcome move since only 18 people were administered the mixed vaccines before the error was identified. This study in India will help us understand if the same approach can be adopted for COVID-19, an infectious disease that requires cohesive, stepped-up actions. A positive result will be pathbreaking – it will help India address the issue related to the supply of vaccines and allow a larger number of people to get vaccinated and break the chain of transmission faster," Narayan said.