Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period

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by Kujo17

Source Harvard Univ via ScienceMag

Abstract

It is urgent to understand the future of severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) transmission.

We used estimates of seasonality, immunity, and cross-immunity for betacoronaviruses OC43 and HKU1 from time series data from the USA to inform a model of SARS-CoV-2 transmission.

We projected that recurrent wintertime outbreaks of SARS-CoV-2 will probably occur after the initial, most severe pandemic wave. Absent other interventions, a key metric for the success of social distancing is whether critical care capacities are exceeded.

To avoid this, prolonged or intermittent social distancing may be necessary into 2022.

Additional interventions, including expanded critical care capacity and an effective therapeutic, would improve the success of intermittent distancing and hasten the acquisition of herd immunity.

Longitudinal serological studies are urgently needed to determine the extent and duration of immunity to SARS-CoV-2.

Even in the event of apparent elimination, SARS-CoV-2 surveillance should be maintained since a resurgence in contagion could be possible as late as 2024.

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This study, like most, has a lot of info so posting snippets out of context isnt always effective however these 4 notes within this study stuck out to me. For those of us without substantial education in these fields it’s hard to “read” through these studies but often the message is pretty clear if the authors take this into account. The following are 4 paragraphs from full study available in link above. Granted the full study is not solely about the info withi these sections I found the points made fairly relevant to us now and definitely something to be considering given the current unknowns

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SARS-CoV-2 can proliferate at any time of year

In all modeled scenarios, SARS-CoV-2 was capable of producing a substantial outbreak regardless of establishment time. Winter/spring establishments favored outbreaks with lower peaks, while autumn/winter establishments led to more acute outbreaks (tables S2 to S4 and fig. S7). The five-year cumulative incidence proxies were comparable for all establishment times (tables S2 to S4).

If immunity to SARS-CoV-2 is not permanent, it will likely enter into regular circulation

Much like pandemic influenza, many scenarios lead to SARS-CoV-2 entering into long-term circulation alongside the other human betacoronaviruses (e.g., Fig. 3, A and B), possibly in annual, biennial, or sporadic patterns over the next five years (tables S2 to S4). Short-term immunity (on the order of 40 weeks, similar to HCoV-OC43 and HCoV-HKU1) favors the establishment of annual SARS-CoV-2 outbreaks, while longer-term immunity (two years) favors biennial outbreaks.

If immunity to SARS-CoV-2 is permanent, the virus could disappear for five or more years after causing a major outbreak

Long-term immunity consistently led to effective elimination of SARS-CoV-2 and lower overall incidence of infection. If SARS-CoV-2 induces cross immunity against HCoV-OC43 and HCoV-HKU1, the incidence of all betacoronaviruses could decline and even virtually disappear (Fig. 3D). The virtual elimination of HCoV-OC43 and HCoV-HKU1 would be possible if SARS-CoV-2 induced 70% cross immunity against them, which is the same estimated level of cross-immunity that HCoV-OC43 induces against HCoV-HKU1.

Low levels of cross immunity from the other betacoronaviruses against SARS-CoV-2 could make SARS-CoV-2 appear to die out, only to resurge after a few years

Even if SARS-CoV-2 immunity only lasts for two years, mild (30%) cross-immunity from HCoV-OC43 and HCoV-HKU1 could effectively eliminate the transmission of SARS-CoV-2 for up to three years before a resurgence in 2024, as long as SARS-CoV-2 does not fully die out (Fig. 3E).

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