Back in May, I wrote a post “Covid-19: may be endemic” in which I said
Like measles, covid-19 could become endemic. Never dying out entirely. Needing to be controlled in human denser populations into the indefinite future.
The Standard: “Covid-19: may be endemic“
and
That is where I think that this disease will wind up. If I had to bet, and assuming a vaccine, I’d say this will eventually be more prevalent than measles, and less frequent outbreaks than the annual flu. It will be endemic.
The Standard: “Covid-19: may be endemic“
That certainly seems to be where this virus is heading. Vaccinating the worlds population to the point that the disease can’t find human hosts to spread to increasingly seems unlikely.
The kind of viral recombination variants (like B.1.1.7 recognised in the UK, and B.1.351 recognised in South Africa) that we are seeing now indicate that a deep penetration into human populations. Certainly sufficient to allow enough shuffling of features from different viral strains to cause a moving target for vaccine immunity and for recovery immunity.
Viral recombination occurs when viruses of two different parent strains coinfect the same host cell and interact during replication to generate virus progeny that have some genes from both parents. Recombination generally occurs between members of the same virus type (e.g., between two influenza viruses or between two herpes simplex viruses). Two mechanisms of recombination have been observed for viruses: independent assortment and incomplete linkage. Either mechanism can produce new viral serotypes or viruses with altered virulence.
Medical Microbiology. 4th edition.
While the emergent effect of recombination strains is often considerable, the effect is usually to cause strain on expected medical capacities, and ignorant barking by stupid politicians (National’s Chris Bishop gave a fine example of such stupidity before New Year).
The Economist has a good leader article on the endemic probabilities of Covid-19. While it is paywalled, you can probably read it without a subscription after jumping through some hoops.
Even miracles have their limits. Vaccines against the coronavirus have arrived sooner and worked better than many people dared hope. Without them, the pandemic threatened to take more than 150m lives. And yet, while the world rolls up a sleeve, it has become clear that expecting vaccines to see off covid-19 is mistaken. Instead the disease will circulate for years, and seems likely to become endemic. When covid-19 first struck, governments were caught by surprise. Now they need to think ahead.
The Economist: “How well will vaccines work?“
Which is really going to be an issue with some of the political idiots. Especially those politicians on the right who seem to see a virus as being part of a cultural war rather than something that they can deal with. The level of idiotic foot-dragging by conservative and right-wing politicians in many countries has, in my view, been the primary reason for the depth of the covid-19 pandemic.
The late and half-hearted responses to the spread of a new disease back in the first quarter on 2020 were led by conservative politicians more concerned about short term effects on their economies and election chances than on any clear understanding of disease spread. The crux of the issues that point toward the pandemic reducing to an endemic disease are explained well.
… Although vaccines fail to prevent all mild and asymptomatic cases of covid-19, they mostly seem to spare patients from death and the severest infections that require hospital admission, which is what really matters. Early evidence suggests that some vaccines stop the virus spreading, too. This would greatly slow the pandemic and thus make it easier to alleviate lockdowns without causing a surge of cases that overwhelms intensive-care units. Those findings, and many more, will harden up over the next few months as more data emerge (see article).
However, despite all this good news, the coronavirus is not finished with humanity yet. Covid-19 will continue to circulate widely. There is a growing realisation that the virus is likely to find a permanent home in humans, as “The Jab”, our new podcast, which launches on February 15th, will explore. That has profound implications for how governments need to respond.
One reason the coronavirus will persist is that making and distributing enough vaccine to protect the world’s 7.8bn people is a Herculean task (see article). Even Britain, which is vaccinating the population at a faster rate than any other big country, will not finish with the over-50s until May. To add to the burden, the potency of a jab may fade, making boosters necessary. Outside the rich world, 85% of countries have yet to start their vaccination programmes. Until the billions of people who live in them have felt the prick of a needle, which may not be before 2023, they will remain fuel for the virus.
Another reason for covid-19’s persistence is that, even as vaccines are making sars–cov-2 less infectious and protecting people against death, new viral variants are undoing some of their good work. For one thing, successful variants are more infectious—anything from 25-40% in the case of b.1.1.7 which was first found in Britain. Infection is governed by the dizzying mathematics of exponential growth, so cases and deaths accumulate rapidly even if the variant is no more deadly. To get a given level of viral suppression, more onerous social distancing is needed.
In addition, new variants may withstand current vaccines. The ones found in Brazil and South Africa may also be defeating the immunity acquired from a previous covid-19 infection. The hope is that such cases will be milder, because the immune system has been primed by the first encounter with the disease. Even if that is true, the virus will continue to circulate, finding unprotected people and—because that is what viruses do—evolving new strains, some of which will be better at evading the defences that societies have mounted against them.
And the third reason sars–cov-2 will persist is that lots of people will choose to remain a target by refusing vaccination. A total of 10m Britons are vulnerable to the disease, because of their age or underlying conditions. Modelling suggests that if just 10% of them declined to be vaccinated and if social distancing were abandoned while the virus was still liable to circulate at high levels, then a tremendous spike in infections and deaths would result.
The Economist: “How well will vaccines work?“
An excellent summary of the difficulties involved trying to make covid-19 a rare rather than an endemic disease.
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