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The severe acute respiratory syndrome coronavirus 2 (SARS – CoV – 2) causes an acute infection that is controlled by the immune response. The virus has a dominant surface protein that is highly immunogenic and it can be assumed that neutralizing antibodies will prove to be the correlate of protection, supported by cell-mediated immunity.1 Therefore, it should be easy to produce a vaccine against this new virus.
This perspective has turned out to be true, but it is the pace at which vaccines have been prepared and administered that is spectacular. Consider that the 2009 H1N1 pandemic influenza virus vaccine was delivered in record time, but the first wave of cases had disappeared before it could be implemented.two The flu vaccine has the distinct advantage that its license is based on a variation of the existing product license and therefore can bypass much of the lengthy and detailed regulatory review required for a new vaccine. Credit should be given to the flexibility shown by expert regulators prepared to conduct an ongoing review of the licensing process for each SARS – CoV – 2 vaccine rather than waiting for massive files of data to be delivered to them at a time. determined. Great credit should also be given to the developers of new vaccine platforms who accelerated their plans to bring us vaccines to protect us against the 2019 coronavirus disease (Covid-19) long before traditional methodology such as killed vaccine, live vaccine attenuated or recombinant glycoprotein. more adjuvant they were able to administer. One platform is based on RNA technology, while the second uses recombinant adenovirus, neither of which has previously led to a licensed vaccine product.3-6
By modifying RNA to enhance expression of the encoded desired immunogen, a chemically defined pathway has been provided for making vaccines from far fewer and less complex molecules, including the self-amplification feature by including the option to encode an RNA polymerase within the RNA molecule. .7 Post-injection degradation is reduced and uptake into target cells is increased by physical incorporation of the modified RNA into lipid nanoparticles.
Using adenovirus as a vector, the recombinant SARS-CoV-2 spike protein is presented to the immune system. To avoid the problem of pre-existing immune responses to the vector that neutralizes the inoculum, the Oxford group used a chimpanzee adenovirus , while the Russian Sputnik vaccine used human adenovirus 5 and then human adenovirus 26 in an initial boost strategy.5, 6
What does this amazing progress tell us about the next steps in vaccinology? First of all, we must consider that these two new platforms are at the top of the list when considering how to develop a new vaccine against the next new virus. This does not mean that conventional vaccine production routes should be discarded; an inactivated vaccine may have a role for non-enveloped viruses that grow well in cell culture, as in the successful hepatitis A vaccine. However, the main assumption for obtaining live attenuated vaccine strains is that they should give better immune responses than Non-replicating preparations should no longer be taken for granted, given the excellent humoral and cell-mediated immune responses generated by the new recombinant adenovirus and RNA vaccines. Second, we cannot allow a return to the old ways of taking decades to develop new vaccines. This not only increases the cost of the final product, but also hurts the profitability assessment. Vaccines are often great value for money, but are held back when calculating the net present value of your future medical benefits. The reason is that public bodies making investment decisions discount the value of future earnings to compensate for the disappointment of having to wait for delivery. This process automatically disadvantages products with a long lead time, such as conventional vaccines. The ‘new normal’ we return to after the lockdown will not include all aspects of the measures taken to obtain SARS – CoV – 2 vaccines during a pandemic, but some must be used again. For example, countries that preorder doses of a vaccine if it is shown to meet defined criteria for safety and efficacy will support investment decisions by vaccine manufacturers. We must encourage our individual countries to come together around the list of viral diseases that the World Health Organization would like to see controlled and tackle them one by one. My preference for the next acute viral infection that spreads through the respiratory tract that causes serious illness with unmet medical need and has a prominent glycoprotein protruding through its lipid envelope would be respiratory syncytial virus, but readers may prefer targets alternative.
