Population Immunity More Important for Controlling Transmission of COVID-19 Than Individual Vaccination Status


Rising inhabitants immunity decreased transmission of COVID-19 and allowed for reductions in quarantine and testing, encouraging 2-dose vaccine and booster uptake.

Sustaining excessive inhabitants immunity, ideally by booster uptake, is important in figuring out acceptable quarantine length for controlling the unfold of SARS-CoV-2, in accordance with a examine not too long ago revealed in PNAS Nexus.

The CDC’s discount of the really helpful 7-day quarantine for shut contacts of a COVID-19 case to five days for the unvaccinated and no quarantine for the vaccinated could not successfully mitigate transmission, in accordance with the authors. Quarantine and testing methods have been discovered to rely on the incubation interval and the transmissibility and stage of inhabitants immunity towards an infection.

Researchers in contrast the likelihood of post-quarantine transmission and the efficient replica quantity with serial testing and isolation for the unique SARS-CoV-2 pressure and three variants of concern, Alpha, Delta, and Omicron, at totally different ranges of vaccination. The comparability of the variety of post-quarantine secondary infections between vaccinated and unvaccinated people demonstrated that the impact of vaccination standing of a person had solely a restricted impact on quarantine length.

Vaccinated instances have been much less more likely to exhibit signs than unvaccinated instances, which resulted in much less frequent self-isolation. The decreases in case detection and self-isolation elevated the likelihood of releasing an infectious case from quarantine.

Variants of concern produced elevated transmission and earlier transmission within the illness time course than the unique SARS-CoV-2 pressure, difficult the effectiveness of present quarantine and testing methods. The findings additionally advised that figuring out optimum illness management methods additionally will depend on the extent of inhabitants immunity.

Rising inhabitants immunity by vaccine and booster uptake was discovered to mitigate transmission. Enhancing 2-dose vaccine uptake led to a considerable lower within the likelihood of post-quarantine transmission throughout serial testing. Rising uptake of 2-dose vaccines additionally notably decreased quarantine durations.

Nevertheless, growing booster uptake solely offered substantive profit to serial testing in comparison with quarantine. The lower in likelihood of post-quarantine transmission concomitant with a rise in booster uptake was discovered to decrease as quarantine length lengthened.

The effectiveness of serial testing in decreasing transmission was drastically improved by a rise in booster uptake, in accordance with the examine.

Researchers discovered that scaling up vaccine-acquired immunity from no vaccination to 100% booster consumption yielded a discount in quarantine by 6 days for the unique SARS-CoV-2 pressure, however solely yield a 2-day discount in quarantine for the Omicron variant. In a inhabitants with 100% 2-dose vaccination, scaling up booster consumption may justify a discount of quarantine by as a lot as 3 days.

Nevertheless, boosting solely has a average impression of quarantine length for Omicron, reducing it by virtually a day. Rising booster uptake may end up in vital variations within the required frequency of serial testing.

Elevated 2-dose vaccine uptake additionally justified decreased surveillance by serial testing, in accordance with the examine. Moreover, the findings advised that speedy antigen testing requires a frequency of each 6 days to curtail transmission inside a inhabitants that’s 100% boosted, encouraging booster uptake.

General, a person’s vaccination standing was discovered to have restricted affect on post-quarantine transmission in comparison with vaccination protection of the inhabitants. Rising inhabitants immunity by vaccination not solely decreases transmission, however also can permit for substantial rest of necessities for quarantine and testing.

The authors observe that surveillance of the immunological standing of the inhabitants is far more essential than the standing of the quarantined particular person when figuring out efficient quarantine durations. They advocate continued efforts to manage vaccines and booster doses to reduce the burden on well being care techniques and forestall massive outbreaks with rising variants of concern or their subvariants.


Wells C R, Pandey A, Gokcebel S, et al. Quarantine and serial testing for variants of SARS-CoV-2 with advantages of vaccination and boosting on consequent management of COVID-19. PNAS Nexus. 2022;1(3). https://doi.org/10.1093/pnasnexus/pgac100


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