Covid-19 Vaccines: Back to Normality?
07 Dec 2020
Any vaccine that achieves a 90% efficacy is remarkable. But to develop it within six months and get it right the first time takes us into uncharted territory. Then to have three, and even perhaps more in the fullness of time, marks this as a significant achievement for science and mankind. But what barriers do these vaccines still need to overcome until we can reach a sense of normality again?
Efficacy vs Effectiveness
Regulators and safety: what boxes still need to be ticked?
This also engenders confidence that the vaccines are safe and encourage people to voluntarily take the vaccines, which is key to achieve widespread vaccine coverage necessary to achieve population immunity.We would expect that all safety concerns are ironed out before full o unconditional approval. These will be relating to injection site side effects but also general side effects such as headaches, fever and malaise, as well as rarer side effects such as antibody disease enhancement (ADE) where the vaccine potentiates the immune system to over-react and worsen the disease. Thankfully the data we have seen thus far allays many of these concerns, which is why the emergency use authorisation has been granted for the Pfizer/BioNTech vaccine, but we have to keep an eye on all the incremental data on this vaccine and the others in late stage development.
The clinical trials are not over. Trial participants will continue to be monitored. Safety issues will be noted. Efficacy of the vaccines will thus change over time. These post-approval surveillance, typically known a Phase IV clinical trials, are important to answer some of the outstanding questions: for how long does immunity last, and are there rarer safety concerns that might crop up? And there are many other questions still to be answered.
Manufacturing, distribution and storage
Logistics loom as the next big challenge after manufacturing. This is where the nuances of the different vaccines come into play. Messenger RNA (mRNA) vaccines need to be stored at between -20 degrees Celsius for the Moderna vaccine and -70 degrees Celsius for the Pfizer vaccine. There is already a concerted effort to put in place cold chain storage and transportation facilities to be able to deal with these challenges.
Manufacturing, distribution and storage
What other questions are still unanswered?
The threat of litigation will temper the enthusiasm of many pharmaceutical companies to expedite vaccine development or over-promise. Although the allure of being first to market remains, given potential for large profits and a reputational boost, if the vaccines were later discovered to be harmful, legal battles could prove more damaging than any potential benefits.
And so despite promising data, we would expect pharmaceutical companies, and regulatory agencies, to exercise caution and restraint in the face of political pressure.Perhaps we could see guarantees against litigation for any long term effects of a vaccine being negotiated by these companies. This would be good for the companies to press on with potentially life-saving therapies in the midst of a pandemic, but will it inspire confidence in the vaccine itself?
Another challenge will be the equitable distribution of a successful vaccine. Many poor countries may not be able to afford a vaccine, even at the cost of production. Other countries may be able to afford the vaccine but not manufacture on its own. The WHO is co-ordinating an effort to make sure such countries are not at the back of the line. And that is crucial in a globally connected world, countries with unvaccinated populations could continue to seed infections in the rest of the world. The concept of herd immunity for a pathogen that spreads as easily as Sars-Cov-2 makes more sense in a global rather than country-specific context.
Outlook for the future
Vaccines will most probably make the biggest difference in how we live with Covid-19 though perhaps not eliminate it in the next few years. Immunity to coronaviruses tends to wane over time. Coronaviruses can also mutate, sometimes to be weaker, other times to be more infectious or deadly, or both. Sars-Cov-2 is likely to become a seasonal virus – the fifth endemic coronavirus. And so vaccination is likely to be a recurring procedure, much like the annual flu jab.
Nevertheless, we have come a long way, science has achieved much, and the resolve to succeed remains as strong as ever giving us hope for a better future.