Rolling out Covid vaccine will need a roadmap

Dinesh C Sharma

Science Commentator

THE Covid-19 pandemic does not appear to show any significant signs of abatement. Many countries in Europe are reporting a second wave of the pandemic, as projected earlier. In India, the number of new infections is rising at a slower pace, but some states like Delhi are experiencing an upward trend. During the ongoing festival and marriage seasons, adherence to social distancing and the use of masks has been reported to be low. This could result in cases shooting up in the coming days and may force the authorities to reimpose some restrictions. Amidst this scenario, any new development on the vaccine front is welcome. In the past few days, leading players like Pfizer and Moderna have announced encouraging results about their vaccines. Though these are not the final outcome of clinical studies, but are enough to give the world some hope in the prevailing gloomy atmosphere. However, the path ahead for vaccines is not going to be easy.

For a virus that causes serious disease with no treatment or cure, vaccine is the predominant way to control its epidemic. Viruses continue to transmit from one human host to another as long as there are susceptible hosts in a given population. The chain of transmission can be disrupted when the number of people with immunity to the virus grows to a significant level in the community. This immunity can either be acquired naturally through infection itself or artificially through a vaccine. Covid infections continue to rise because most of the population is susceptible to the virus. As far as those who have got immunity through infection are concerned, it is still unclear how they will remain immune. Under these circumstances, a Covid vaccine capable of generating lasting immune response would be an ideal solution. Otherwise, repeated shots of the vaccine would become necessary to achieve and sustain immunity. As per present understanding, Covid vaccines under development will require two to three doses for reaching the desired level of immunity.

Given unprecedented scientific and commercial interest in Covid vaccine development, scientists and policy makers are reasonably sure of more than one effective and safe Covid vaccine becoming available sometime over the next one year. The process of taking any vaccine from the lab to the market is complex. First and foremost is the need to generate safety and efficacy data that could meet global regulatory requirements. Then comes the challenge of mass manufacturing of the vaccine. In the case of potential Covid vaccines, pandemic-scale manufacturing is necessary which means capacity to churn out hundreds of millions of vaccine doses. Vaccine companies need huge capacities, massive supplies of vaccine ingredients as well as vials, packing material etc. — all of which are under strain due to the pandemic itself and heightened demand. Some of the promising vaccines use new technologies like ‘messenger RNA’ which have never been used in commercial scale vaccine manufacturing. Making millions of doses of consistently high quality vaccine doses is going to be a challenging task, particularly for vaccines based on biological materials. Biotech vaccine firms are working out tie-ups with contract development and manufacturing organisations for mass production of their vaccines.

Once the vaccine is manufactured, the next biggest task will be its distribution to every nook and corner of the country. Most of the vaccines are sensitive to heat and light. They need to be stored and transported at a certain temperature — ranging from zero to 8 degrees — up to the last point. That’s why cold chains are needed for vaccines, and this has been a big issue in universal immunisation programmes. Any gaps in cold chain could spoil the potency of a vaccine and render it ineffective. Covid vaccines under development will also need to be stored at sub-zero temperatures. In the case of the recently announced mRNA vaccines, ultra-cold chains going up to minus 70 degrees would be needed. Such vaccines, even when they become available, could prove to be logistical nightmares for health authorities. Tropical countries in Asia and Africa need ‘warm’ vaccines which can be easily stored and transported to points of delivery. Development of such vaccines is at a nascent stage. Meanwhile, countries will have to invest to expand the existing cold chains and build new ones for mass rollout of Covid vaccines whenever they become available. The existing distribution infrastructure is designed for child immunisation and not for handling the entire population.

In addition to larger questions of accessibility and affordability of Covid vaccines and the government’s ability to finance population-wide vaccination, issues relating to acceptance of vaccines and vaccine hesitancy will also need to be addressed. The experience of a long battle against polio shows that convincing people to vaccinate children against debilitating diseases can be a Herculean task. Anti-vaccine sentiments have been reported from certain pockets in the country, in the case of childhood vaccines. In a survey conducted by Local Circles in India, 61 per cent respondents said they were sceptical about the Covid vaccine and would not rush to take it even when it may become available in 2021. Such perceptions and attitudes towards vaccination could be problematic because suboptimal deployment of Covid vaccine will not end the pandemic since the virus could still thrive among the unvaccinated susceptible groups of population. In any case, adherence to physical distancing and masking will have to continue as no vaccine is going to achieve zero transmission. Yet another task would be to monitor adverse reactions in people post-vaccination. Even vaccine proven safe in clinical trials may trigger unknown reactions in some when administered to a range of people across ages and with other underlying health problems.

India is better placed in the race for vaccine development and has large vaccine manufacturing capacities. The country is also participating in other global vaccine projects and platforms created for Covid vaccine availability. The time till an effective and safe vaccine becomes available should be utilised to beef up manufacturing, distribution, cold chain and other logistic arrangements, as also mechanisms to ensure equitable access to it. At the same time, preventive measures like wearing masks should continue.