key: cord-0806973-9cww5lka
authors: Mortimer, Philip P.
title: Is there light at the end of the Covid‐19 tunnel?
date: 2020-10-01
journal: Rev Med Virol
DOI: 10.1002/rmv.2173
sha: ad38d17290235c89247e6b63fd0479071aae0ee6
doc_id: 806973
cord_uid: 9cww5lka

nan

In at least one respect, the development of safe and effective vaccines, the advanced economies have acted swiftly, encouraging scientific innovation and funding new approaches to human immunisation. Most of these countries have also sought to contain SARS-2 virus spread through lockdown, but with a variable success that has left the majority of their populations now reliant on early vaccine approval and an adequate product choice as the only escapes from lockdown's associated economic and social harms. A few other developed economies, and many developing ones, have either not chosen or not been in a position to adopt lockdown; but in so far as these countries have a younger demographic profile they have not been overwhelmed by Covid-19 related illnesses. Nonetheless, global Covid-19 mortality is already approaching a million, inviting historical comparison with former years that saw genomic shifts in influenza A.

Both the developed and developing worlds now look forward to seeing the first safe and protective vaccines in 2021, and expect virus near-elimination soon thereafter; but the prospect of this happening depends on the availability of vaccines now in preparation, their cost, their abundant provision and their uptake. There is some background experience of conventionally prepared veterinary coronavirus vaccines and this may be of predictive value as regards immunogenicity. 1 Furthermore, political pressures and financial incentives have since stimulated multinational companies to explore more modern and diverse approaches to vaccine production.

Several of these products have now reached the third phase of evaluation, 2 and it is fair to assume that one or two at least of them will meet immunogenic criteria and once they have been shown to be safe begin to be offered to vulnerable populations. 3 However, vaccine-associated morbid enhancement by respiratory virus vaccines was an issue in the early development of a respiratory syncytial virus vaccine, and this phenomenon cannot be ignored as regards SARS-2 virus no matter how strong the political pressures. More especially, safety has to be ensured if Covid-19 vaccines are to be pressed upon younger, healthier cohorts so as to establish herd immunity.

Whether the vaccine uptake will actually ensure a rapid global retreat of SARS-2 virus also remains open to question. In the medium term (i.e., an interval of a few years rather than just months) the aim must be to establish a population immunity that includes age groups for whom SARS-2 infection constitutes a near negligible risk, and this will involve children whose parents may doubt the value of adding Covid-19 vaccine to an already crowded vaccination schedule. There will be non-compliance: universal immunisation against Covid-19 is not a foregone conclusion. 

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