Vaccines have proven to be effective against the SARS-CoV-2 virus in preventing serious illness and death. In an article published in Nature Medicine on June 9 , an analysis of data from the United Kingdom, gathered between December 1, 2020 and April 30, 2021 when the alpha variant was predominant, showed that the AstraZeneca vaccine had an effectiveness of 64% after one dose and 79% after two doses, in protecting against severe illness and death. In the same article, the authors also found that a previous infection with SARS-CoV-2 had a significant protective effect against re-infection.
Vaccine data
On June 14, Public Health England released a report that showed that the AstraZeneca vaccine had an effectiveness of 71% after one dose and 92% after two doses in protecting from hospitalisation due to the delta variant. In the first report of vaccine effectiveness from India, researchers from the Christian Medical College, Vellore, Tamil Nadu, reported an analysis of 8,991 staff who had been vaccinated between January 21, 2021 and April 30, 2021, predominantly with Covishield, in the Mayo Clinic Proceedings . The protective effect of vaccination was 92% against need for oxygen and 94% against need for intensive care. There were no deaths, but about 10% of those who had received one or two doses were infected. Although sequencing was not available, many breakthrough infections were probably due to the delta variant strain. These data from the United Kingdom and India show that the Covishield vaccine is working against the variants.
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More detailed studies on whether the vaccines are continuing to work, if yes, for how long, or against new variants, will continue to be needed. We also need to consider what we expect from vaccines at different stages of the pandemic. At the level of the individual, we expect vaccines to be safe and provide protection from disease and death at least, and preferably also from mild disease and infection. From the point of view of public health, we expect vaccines to decrease the burden of illness and spread of infection. For society, however, beyond the needs of public health, the ability to go back to productivity and social interactions also matters. These different needs require policy approaches that balance the achievement of health and societal goals with the potential impact, and the exigencies of supply constraints.
In a time of urgent need and short supply, a clear and measurable goal is essential. The prioritisation and delivery strategy needs to align with the goal to achieve maximum impact. We have been somewhat confused about the goal, with early announcements of vaccinating 300 million people being replaced by all adults. With the increase in highly transmissible variants, it is clear that to both prevent disease and slow spread, we will need to cover a larger proportion of the population, possibly extending at a later stage to children.
On herd immunity
When vaccines seemed to be somewhere in the future with no predictability on timing or supply, discussions on the pandemic focused on ‘herd immunity’ or the percentage of the population that needed to be infected or vaccinated in order to slow the spread of infection. The Swedish strategy of limited restrictions and the Great Barrington declaration attracted much opprobrium as many scientific commentators considered it callous to follow a strategy which meant that a lot of people would get infected with the virus. Herd immunity or herd effect or herd protection is an often misunderstood term, but a key attribute is that the more transmissible the agent, the higher the level of the population that needs to be infected or vaccinated. With the delta variant, it is clear that the earlier plan to vaccinate a smaller proportion of the population is not appropriate and reaching up to 85% of the population might be necessary. This implies that not only will we have to consider all adults but we should be planning for children as well.
Long- and short-term goals
The control of infection in the population is the long-term goal. The short-term goal is to protect individuals at highest risk and to save lives. The deaths from COVID-19 show clearly that those who are the oldest are at the greatest risk of severe disease and mortality, with distinct stratification of severity by age, followed by those with comorbidities such as diabetes mellitus and hypertension. Yet, the risk of severe disease and death among younger people, though low, is not zero and therefore when large numbers of young people get infected some of them will die even with the best medical management. Nonetheless, the goal of preventing the maximum number of severe cases and deaths clearly requires an age descending approach.
This was indeed the strategy that was initially implemented in India, but the opening of the age tiers has not kept pace with the supply. The Government has not revealed a clear road map of availability of vaccines and their supply to individual States. This has highlighted the reluctance by the Government of India to reveal information which would help in formulating a predictable delivery mechanism that could be communicated to citizens. Coupled with the anti-science statements made by those seen as close to the Government, this has led to a situation where the public is confused as to how best to cope with the novel coronavirus pandemic. With the promise of vaccines as at least a partial solution, but with no certainty on availability, doubt, fear, anxiety and depression are widespread.
To move forward, we must accept that it is extremely unlikely that we will achieve the goal of vaccinating every adult by the end of 2021. Therefore, based on the principles of public health, we must vaccinate those most at risk from serious illness and death first. Based on population pyramid data, we can extrapolate that there are about 360 million above the age of 45 years. Even though recent data from the United Kingdom with the delta variant indicates a slightly lower effectiveness against severe disease requiring hospitalisation with a single dose ( 71% with one dose and 92% with two doses ), the high rates of previous exposures in India may make it feasible to immunise a large part of our population with a single dose, at least initially.
Rural focus
The final prioritisation and approach should be modelled before policy is made and implemented, but for delivery, a rural focus is key. We must take the vaccine to every village, building on the experiences of the pulse polio programme and conducting elections. Community leaders should be empowered with information and tools to broadcast the message that the vaccine saves lives. The central government has centralised vaccine purchase but must revisit the private sector allocation and cede distribution to States, providing support when requested. The CoWIN app must not be a limiting factor on access to the vaccine.
Evidence, models, good data
As more vaccines become available the vaccination policy must be adapted quickly to changing circumstances. We must generate evidence and develop models to design the appropriate vaccination strategy for younger populations. If cases are climbing in a particular region, we should direct vaccine doses there to protect as much of the population as possible and decrease both disease and further spread. High vaccination coverage in cities may protect rural areas. Some professions are most likely to spread infection and should therefore be prioritised for vaccination.
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Finally, the Government must trust its citizens and share the information that is solely available to it. A notable aspect of the pandemic is the absence of credible data from the government. This has led to speculative ideas based on poor or poorly understood information and misinformation. The management of the pandemic has been severely impacted by this lack of granular, interpretable, actionable data. We need to restore society to normalcy. Good data, or the ability to measure what matters, is the key.
Dr. George Thomas is the former editor of The Indian Journal of Medical Ethics ; Dr. Gagandeep Kang is Professor, Wellcome Trust Research Laboratory at the Christian Medical College, Vellore; Dr. Jayaprakash Muliyil is former Principal of the Christian Medical College, Vellore
Published - June 19, 2021 12:02 am IST
