Mix and match COVID-19 vaccines: potential benefit and perspective from India.

Vaccination against COVID-19 infection has recently been launched all over the world. Getting the right vaccines into the right people at the right time during a pandemic is, unsurprisingly, proving to be a logistical challenge. There are multiple types of COVID-19 vaccines including inactivated virus, virtual vector-based and RNA-based vaccines. Most of the current vaccination regime includes a second homologous booster dose following a priming dose at a month interval. The recent interest in mixing of COVID-19 vaccines born of necessity stems for the aim of increased protection,1 simplifying immunisation efforts for countries facing fluctuating supplies of the various vaccines and its judicious utilisation, but has a risk of increased side effects and most importantly, a lack of evidence. The concept of vaccine mixing is not something new but has been previously used for multiple illnesses including HIV, malaria, Ebola and influenza.2 ‘Heterologous prime-boost vaccination’ involves delivery of the same or similar antigens of the disease-causing agent through two different vaccine types with the first dosage being used to prime the immune system while the subsequent dosage using different vaccine types to boost the immune response. This aims to increase the protective efficacy and rationalise the usage of the available vaccines. Mixing two different vaccines can also elicit a strong …