The question that covid fatigue periodically comes back to us is always the same: how and when will it end? If it is not yet possible to express with certainty on the times, it is however very likely that we will not get rid of the new coronavirus disease out of the blue.
It will rather be a long goodbye, preceded by – hopefully – an increasingly manageable coexistence with SARS-CoV-2. In other words, given the very high prevalence of covid, it is difficult for vaccines to be able to eradicate it completely. More realistically, the disease will become endemic. It is the scenario outlined in an article on The Conversation, which also explains what is meant by endemic.
Can we get rid of covid without a vaccine?
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Covid, how it will end: a change of pace. The fact that large numbers of people on Earth have not yet contracted the infection indicates that the new coronavirus still has enough “material” to continue circulating for some time. As cynical as it may seem, we are nothing more than viruses walking replication tools. In the coming months, the prospect of a series of vaccines capable of limiting infections, together with that of a certain immunity at a great price acquired by the population, they should begin to slow down the pathogen’s path.
But his departure from the scene will not be sudden. In densely populated areas or with still a high number of people susceptible to infection, covid will continue to circulate at a sustained level. When acquired immunity and control measures succeed in bringing the rate of contagiousness (Rt) to a level equal to or less than 1 – that is, each individual infects at most one other person – the infection will stabilize at a constant and easily predictable level. It will always be present in certain communities, but with a low prevalence.
How effective should a vaccine be to stop the pandemic?
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Endemic diseases: the characteristics. Excluding sexually transmitted diseases or pediatric infections, which are present and active almost everywhere albeit to varying degrees, today most infections are endemic in certain geographic areas: elsewhere, public health interventions have eliminated infection or the conditions it needs to circulate. This is the case with malaria, dengue, Zika and many other diseases transmitted by mosquitoes, which have become endemic in tropical regions.
Endemic diseases are characterized by recurrent spread patterns. Some spread more frequently in certain seasons (think of the flu), others alternate periods of greater transmission with periods of low transmission and all continue to circulate as long as there is a pool of people not yet infected. The presence of pockets of the population more susceptible, because in geographic areas initially spared from the bulk of the circulation, continues to feed the endemic as would the embers still burning in a fireplace.
Why get vaccinated against influenza and pneumococcus
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Endemic diseases: what role does immunity play? Infections against which lifelong immunity develops, such as measles, and in which every child born is susceptible until they have received a vaccine, are more prevalent in countries with high birth rates: this is why in areas poorest people in the world do everything possible to get their children vaccinated while in the West, which has now forgotten the consequences of measlesanti-tax movements gain support.
In diseases against which temporary immunity develops, the population periodically loses immunity to become susceptible again: viruses and bacteria have learned to develop mutations to evade the immune barrier, as we see for the flu virus. In these cases, the available vaccines must be updated from year to year to offer the best possible protection. We don’t know how long immunity to the covid pathogen lasts: that in response to other and less serious coronaviruses it runs out after about a year.
Coronavirus: how it ends. If vaccines protect us from the most unfavorable outcomes of covid, the disease could become one of the many from which we are vaccinated or in which we incur at least once in our life. With the difference that by then we may have learned to protect the most fragile people. If vaccines also succeeded in strongly hindering transmission or conferring long-lasting immunity, we could hope for more optimistic, but less feasible scenarios: permanent eradication is a complex challenge even for diseases against which vaccines have been developed. extreme efficacy or permanent immunity (such as measles).
History teaches that often, pandemics end earlier on a social level than on a medical level: tired of being afraid, you get used to their rarer presence. After all, the plague has not been completely erased: it still occurs today in sporadic circumstances, very often treatable with antibiotics.
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