Evaluation of candidate vaccines for COVID-19 should be done on technical parameters and programmatic suitability. An ideal vaccine would provide all of these immunity that is of a high degree (90% + protective especially against severe illness), broad scale (against different variants) and durable (at least five years if not lifelong); a vaccine that is safe (little or no side-effects and definitely no serious adverse effects); a vaccine that is cheap (similar to current childhood vaccines); a vaccine that is programmatically suitable (single dose, can be kept at room temperature or at worst needs simple refrigeration between 2C and 4C, needle-free delivery, and a vaccine that is available in multidose vials, has long shelf life and is amenable to rapid production.
Obviously, a vaccine having all these desirable characteristics is a pipe dream and most vaccines would fare well in some and not so well in other parameters, making it difficult to choose between them. Also, at this stage, we are only looking at a one-time use of this vaccine to stop the novel coronavirus pandemic as the requirement for a regular vaccination (as for influenza) would be somewhat different.
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A difficult vaccine to develop
Historically, we have faced difficulties in the development of coronavirus vaccines. Although there were some attempts at development of vaccines against Severe Acute Respiratory Syndrome (SARS) and the Middle East Respiratory Syndrome (MERS), there are no licensed vaccines for any coronavirus yet. Previous coronavirus vaccines were found to be immunogenic (generate antibodies as in phase II) but did not effectively prevent acquisition of disease (phase III) fuelling a concern that vaccination may not induce long-lived immunity, and re-infection may be possible. There are also safety concerns due to immunological consequences of the vaccine as these vaccines use newer techniques with which we do not have long term or large population experience.
At this stage, it is not possible to comment much on the duration and breadth of protection of COVID-19 vaccine candidates. About the safety of vaccines, there are always possibilities of rare (one in million) or delayed (by months or years) serious adverse events which will come to light only after mass vaccination has started; this requires a good post-licensure surveillance system to be in place. We should be prepared for such eventualities, and a clear policy on their compensation should be framed.
Most could be in two doses
The COVID-19 vaccine candidates by Moderna and Pfizer have already released early information of high effectiveness (90%+). Pfizers two-dose shots need to be stored at minus 70C) something which is beyond Indias current vaccine storage infrastructure. Modernas vaccine is more thermostable and has a requirement similar to what we used for oral polio vaccines. AstraZeneca, also a frontrunner, makes use of simplified storage settings as do many other candidates. As results of phase 3 trials of other vaccines are out, we will be faced with a dilemma of choice (referred to earlier). Almost all of them seem to require two doses.
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Given this complicated scenario, what should the government strategy be while choosing a vaccine and for vaccination?
Ranking by risk category
The first rule would be to not to put all your eggs in one basket. We already know that government has planned for vaccine supply from different sources. The second rule would be to prioritise. The World Health Organization has issued guidelines for prioritisation for vaccine recipients. For this, we need to rank population sub-groups by risk category (risk of infection or adverse outcome or economic impact), and by programmatic ease of vaccination based on their captivity (health-care workers, organised sector, workplace, schools), and access to existing channels of vaccination (pregnant women and children). Start with where these two criteria intersect health-care workers followed by policemen. The third rule is use multiple channels to immunise the population. Other important considerations would be of equity and cost. Obviously, military and paramilitary staff will be dealt with as a special case due to their high captivity and national security considerations.
The first product off the block may not be suitable in terms of cost and cold storage, but if the priority is health-care workers, then we could go ahead and buy some (how much is a trade- off) vaccines for this group if it is above 75% effective, as it is possible to immunise health-care workers keeping cold storage requirements at their own facility, including in private sector or district hospitals. The same infrastructure can also be used to vaccinate the police force. This will buy us some time to evaluate other vaccines and delivery options. The workplace and school-based vaccination roll-out could be the second phase of vaccination.
Models of social mobilisation
Problems will arise as we move towards vaccinating the general population, even high-risk groups (the elderly and those with co-morbidity) in the general population. It might be easier to vaccinate the institutionalised elderly as compared to community-dwelling ones. The only orderly option is to create some sort of a technological solution of a queuing system based on an earlier registration process for age and presence of co-morbidity and allotment of appointment in a nearest booth. It is essential that we avoid overcrowding during vaccination.
However, the greatest challenge would be to immunise the poorest and the most vulnerable (slums/migrants/refugees/people with disabilities). Because of access issues, this must be by an outreach or camp approach (booths along with web-enabled appointments facilitated by civil society); a programmatically suitable vaccine will have to be prioritised for them. We have learnt major lessons through social mobilisation efforts during the Pulse Polio campaigns, Aadhaar card enrolment and elections, which will serve as good models. We have the wherewithal to do it. However, our Aadhaar experience shows that this will take time. Fortunately, for the pandemic to end, we need not have to immunise everybody. It is expected that the pandemic would start receding once we protect about 60% of the population (in terms of coverage x effectiveness). However, we should ensure that this coverage is well-spread out, else focal outbreaks will keep occurring in areas with poor vaccine coverage. This also raises the possibility of using a ring immunisation strategy (immunising the population around reported cases), even earlier.
Dealing with pay and get
One major challenge would be that many people would be willing to pay for the vaccine and ask for expedited access. So, should we allow this? Obviously, till we cover a bulk of phase 1 beneficiaries, the government should not concern itself with other groups. However, it can and should allow the vaccine to be available in the private sector at a market-driven price for such people. It will be ethical as well as cost-saving for the government, if it does not divert vaccines from the government-driven programme. Let the decision to wait for a government-delivered vaccine or one from the private sector be made by individuals, and not the government. It will also free the government to focus more on needy people.
Many countries have already published their prioritisation policy whereas in India, it is only based on what we hear from the media that health-care workers have been prioritised and details are not available in the public domain. It is critical that the government has a fair, transparent and published policy in this regard even if it results in heartburn in some quarters. Choosing, paying for vaccines and their administration by governments are going to be most challenging with no easy answers. And I expect some missteps early in the game. I would not like to be in those shoes, as public criticism is inevitable.
Dr. Anand Krishnan is Professor at the Centre for Community Medicine, All India Institute of Medical Sciences, New Delhi. The views expressed are personal