The priority should be to vaccinate the unvaccinated, says Dr Jerome H. Kim
Two billion doses of Covid vaccines are being produced every month which is not enough for global boosters and primary vaccination campaigns. The priority, therefore, should be to vaccinate the unvaccinated, says Dr Jerome H. Kim, one of the world's leading vaccine experts and Director General of the International Vaccine Institute in an interview to Khaleej Times.
Do we need booster doses before finishing a global two-dose vaccination campaign?
There are a few ways to approach this difficult question. First, WHO (World Health Organisation) and regulatory agencies of different countries have said that boosters are necessary under certain conditions (for the immuno-compromised). Second, 50 per cent of the world’s population have received a first dose.
Many in high-income countries are not being vaccinated, so you would have to do some modelling to say (accurately) that while we are making 2 billion doses of vaccines per month, we don’t have enough to do both boosters and additional primary vaccination. Third, have we ensured vaccine delivery to the 96 per cent of inhabitants in low-income countries who have not received even a first dose?
Are health systems being improved there to ensure that when a vaccine arrives it is used before it expires. Who will cover the cost of upgrading health systems and what happens if countries are not ready?
Vaccine hesitancy has caused doses of vaccine in non-high-income countries to be destroyed. Finally, what were the COVAX (the global programme for vaccine supplies) doses for: to protect those most at risk. How many doses were we talking about: 2 billion to vaccinate the elderly and health care workers (plus some). If we accomplish that, then the highest mortality cohorts would be protected (against severe infection, hospitalisation and death). So far, COVAX has sent out 500 million doses. We now make more than 1.5 billion doses every month. Why aren’t we able to do both?
There's pressure on governments in the West to go for booster third doses. Shouldn't they wait and watch?
We need to help COVAX achieve its 2-billion dose target. We have to target those countries that have large numbers of people who are unvaccinated and at high risk. Given current rates of vaccine production, why does this remain a problem? Would it be more important to give COVAX what it needs than donating 10 million doses to country X or country Y based on political alignments? Moreover, high and middle-income country governments are looking at data suggesting that the booster doses not only increase the level of protective or “neutralizing” antibodies, but also increase protection against bad outcomes from Covid infection.
Any new vaccine in sight? What next after MRNA?
Bharat Biotech's whole inactivated vaccine, Covaxin (with a new adjuvant) has recently been approved by WHO for emergency use. There are still a large number of vaccines in clinical testing; we have heard recently about the results of DNA vaccines (Zydus Cadila, India), protein vaccines (Clover, China and Zhifei, China) with additional protein vaccines (BioE, India; SK, Korea; Sanofi, France) in phase III (or awaiting approval). A key step will be WHO emergency use listing. An interesting class of new vaccines will be those that are potentially universal Covid vaccines (that should theoretically work against all variants) or multivalent Covid-19 vaccines (combining different variants) that might give you broad protection against the currently known variants (and potentially future variants). Luckily the vaccines we have do develop protective antibody responses against the variants we know of (so far). Farther down the line are universal coronavirus vaccines (that work not only for Covid but also for seasonal coronaviruses and other pathogenic coronaviruses like Mers and Sars-1).
The origins of the coronavirus remain a mystery. Could a more potent vaccine be developed if the origins are known? We are still where we were on the source and early transmission of the diseae.
From the perspective of prevention and treatment the “source” of the coronavirus is a distraction. The forward mutations of the virus (and its implications for current/pending vaccines) is of greater concern than the legacy sequences from December 2019 and January 2020. The new polymerase and protease inhibitors work on all the Covid-19 major variants. The “origin” of SARS-CoV-2 is of interest from a zoonotic disease perspective, or if gain-of-function type work generated it (which still seems unproven and unlikely), then we need to ensure through internationally accepted guidelines and rules that this research be disclosed, controlled, and tightly documented. From the perspective of catastrophic animal to human transmission we should try to understand the origins and evolution if this will help us predict and importantly prevent similar zoonotic transmissions in the future.
Several studies show the potency of vaccines decline as months pass but herd immunity is a factor that cannot be ignored. Are we reaching a stage where this pandemic is now being seen in some countries as endemic? Smaller, localised outbreaks will happen.
We know that the vaccines don’t prevent infection completely, but they do prevent disease (severe infection, hospitalization, death). We haven’t talked enough about vaccines as one element in a comprehensive programme of prevention that still includes masks and distancing (and hygiene) as well as now newer antiviral agents effective orally. We have not been able to break transmission, delta variant may be found at similar levels in the nasopharynx of vaccinated and unvaccinated persons – the vaccinated person is much less likely to be severely ill or die, but can still transmit infection. Masks greatly reduce the risk of transmission, as will isolation of infected cases for a certain period of time. Prompt diagnosis and treatment with antivirals will also help. We need to consider vaccines as an important part of a larger solution, though, and we haven’t communicated that well. Finally, having large pockets of unvaccinated people (rather than having the unvaccinated dispersed evenly in the population) becomes fuel for future outbreaks with inevitable spread to vaccinated populations. The consequences are clear: vaccinated people who become infected have an 11x decrease in hospitalisation and death compared to the unvaccinated. But we have to figure out a better way to limit transmission.
Is eradication of the coronavirus possible?
Until we break the cycle of transmission effectively it will be difficult to eradicate coronaviruses. We don’t know what the “magic” level of population-wide vaccination is that will be associated with herd immunity or how to get greater acceptance of other measures that will, with vaccination, help to stop transmission
Vaccines do not prevent infection. What else can we do?
We developed safe and efficacious vaccines in record time. There is some level of prevention of infection but it is not complete. What do we have to do to develop sterilizing immunity – change the vaccine formulation? Use another vaccine in a mix/match boost? Use a novel vaccine – live-attenuated or a vaccine that stimulates another arm of the immune system (which might also theoretically work on multiple variants)? The use of potent antivirals, in conjunction with continued testing, tracing and treatment (as well as temporary isolation) might also limit spread. It will sound trite but we need to do more research to understand better: a) What types of immune responses are necessary to prevent infection best and for the longest time; b) How to induce these responses; c) How to get higher levels of vaccination in all countries; d) How to get better compliance with physical distancing, hygiene and masks
Could the Nipah virus mutate into the next big pandemic?
Scientists don’t like to answer probabilities with yes or no. Nipah is often mentioned as a possible suspect for the “next pandemic”. It is another bat-borne infection; in the original instance pigs were an intermediary. Human-to-human transmission does occur (primarily among family contacts), though respiratory transmission is thought to occur, contaminated secretions are the more likely source of the virus. Things that make it concerning are its longer period between infection and disease (when unknown infection might be transmitted) and its wider range of potential animal hosts, but currently, it is much less contagious. Its ability to adapt better to human transmission may be increased by population pressures on bat natural habitats in South East Asia. The coronaviruses and paramyxovirus (like Nipah) are widely thought to be potential “next pandemic” pathogens, highlighting the need for more study, better surveillance, and heighten awareness in potentially affected areas.
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