science

Scientists look to develop better jabs as Omicron rages across the world

Scientists look to develop better jabs as Omicron rages across the world

MUMBAI : Scientists are returning to the drawing board to try and develop improved vaccines as governments across Europe and North America rush to control the surge driven by the Omicron coronavirus variant that has dented the protections afforded by the current jabs. To be sure, current vaccine platforms such as the mRNA, adenovirus and the inactivated virus do prevent severe illness. But preventing infection at least in immunocompromised and high-risk groups remains a challenge for public health officials. The incidence of breakthrough infections—i.e among those who are already vaccinated—has also led to discussions in the scientific community to look at mixing vaccines platforms. “The primary metric should be to look at vaccines that prevent severe diseases. But we should also aim at vaccines that reduce overall infection or mild infection, said Dr Sanjay Pujari, director and chief consultant, Institute of Infectious Diseases. Western countries are rushing to protect their populations with a third dose after studies showed waning immunity six months after vaccination. A Canadian study showed that with two doses of Pfizer and Moderna vaccines, protection against Omicron infection dropped to 50%, though it held up against hospitalization and ICU occupancy. Studies with the AstraZeneca vaccine in the UK showed a reduction in effectiveness against symptomatic disease for Omicron compared to Delta. This is where the strategy of mixing doses comes in. A large study in Denmark showed that giving the first dose of ChAdOx (AstraZeneca) followed by mRNA results in better antibody titers. The US Food and Drug Administration authorized the mixing of Moderna’s mRNA vaccine and Johnson and Johnson’s adenovirus vaccines after studies showed better immune response from such mixing. In India, an accidental mixing of Covaxin and Covisheild among 18 individuals in Uttar Pradesh also showed better immunity. In January 2022, a study by CMC Vellore on the immune responses to mixed administration of Covisheild following Covaxin and vice-versa given at an interval of 56+/- 7 days versus two unmixed jabs could throw a light on the strategy. “There is a clear need for trials exploring the safety and efficacy of heterologous vaccines for two reasons. First, available vaccines are targeted for specific components of the virus. Hence, wider actions over a broad spectrum of coverage by different types of vaccines is important. Second, heterologous vaccines build up formidable challenges for a fast-evolving virus. The evolution of variants is easily facilitated by poor vaccination coverage. Next easier target for the virus would be monologues vaccines, said Dr Giridhara babu, head of lifesciences epidemiology, Public Health Foundation of India India is one of the few countries where pharma companies are working on four different vaccine platforms, making it ideal for conducting these experiments. Download.

science 2021-12-21 Livemint