Health system impacts of SARS-CoV − 2 variants of concern: a rapid review

We conducted a rapid review following standardized rapid methodological guidelines [16, 17]. We used an integrated knowledge translation approach, as the question was initially designed by knowledge users and refined with the synthesis team with continuous exchange during the process through regular meetings. The knowledge user partners, who are health system and infectious disease experts, reviewed the results. Patient partners were engaged in the knowledge dissemination phase to provide feedback on the final report and provide recommendations from the patient perspective.

Of the 59 studies, 31 were cohort studies, 20 used a cross-sectional design, and one was a case control study; thus, they were subject to appraisal using the relevant JBI checklists. Among the 51 cohort/cross-sectional studies, five were appraised as low quality [24‐28], 24 as medium quality [29‐52], and 22 as high quality [53‐74]. The case control study was of medium quality [75]. A complete overview of JBI scores by study can be found in Table 1. Of note, six were modeling studies and one was a lab-based study; these were therefore not included in the quality assessment.

Figure 3 provides an overview of studies that explored various aspects of capacity planning in relation to country or region. While most studies related to this sub-question reported on the impact of VOC on hospitalization, admission to ICU, and mortality, six studies reported on outcomes in relation to vaccines. Haas et al. [59] conducted the first nationwide estimates on the vaccine effectiveness (VE) of two doses of the Pfizer vaccine on hospitalization and deaths in Israel during a period of high Alpha prevalence. They found that adjusted VE against COVID-19 hospitalization was 97.2% (95% CI 96.8-97.5), against severe and critical hospitalization was 97.5% (95%CI: 97.1-97.8), and against death was 96.7% (95%CI: 96.0-97.3). AlQahtani et al. [51] compared four vaccines (Astra-Zeneca, Pfizer/BioNtech, Sinopharm, and Sputnik V) and found that all were effective in decreasing risk of hospitalization, ICU admission, and mortality prior to and during the period when Delta was dominant, although the Sinopharm vaccine is less effective than the Pfizer/BioNtech on all outcomes. Agrawal et al. [40] found that in patients with pre-existing medical conditions who were infected with Delta but vaccinated were less likely to die than patients who were unvaccinated (p = 0.002); no difference was found in patients without pre-existing conditions who were infected with either Alpha or Delta. Havers et al. [42] found that hospitalization rates were > 10 times higher in unvaccinated individuals compared to vaccinated individuals during a period of high Delta prevalence. Twohig et al. [70] found that patients with Delta who were unvaccinated or < 21 days since first dose had a higher estimated risk of hospital admission and a higher risk of either hospital admission or emergency care than patients with Alpha; however, there was no significant interaction when comparing between vaccinated and unvaccinated individuals infected with either Delta or Alpha. Veneti et al. [72] found that after adjusting for sex, age group, country of birth, variant and underlying comorbidities, partially vaccinated individuals had a 72% reduced risk of hospitalization (95%CI 59–82%) and fully vaccinated had a 76% reduced risk of hospitalization (95%CI 61–85%) compared to unvaccinated individuals with Delta or Alpha.

Di Domenico et al. also reported on outcomes differently, in that they provided an age-stratified transmission model to estimate the role that curfew measures could have on hospitalization in France [76]. They found that if the epidemic progressed under curfew conditions (6:00 pm nightly, implemented nationwide January 16, 2021) before school holidays and vaccination was accelerated, hospital capacity would be reached around week 13 in France (which had 2.2% Alpha penetration), week 12 in Île-de-France (which had the highest Alpha penetration, 6.9%), and week 14 in Nouvelle Aquitaine (which had the lowest Alpha penetration, 1.7%). This was supported by data. The partial relaxation of social distancing (estimated at a 15% increase in effective reproduction number) would shorten these estimates by at least one week. Stronger social distancing, equivalent to the efficacy measured during the second lockdown (estimated at a 15% reduction in effective reproduction number), would maintain hospitalizations below the peak of the second wave in Île-de-France and Nouvelle Aquitaine but would not be enough to avoid a third wave in France, even under accelerated vaccination (100,000 − 200,000 doses/day). Accelerated (200,000 first doses/day) and optimistic vaccination rollouts (300,000 first doses/day) would reduce weekly hospitalizations by about 20 and 35% in week 16 (i.e., April 19 − 25, 2021) compared to a stable vaccination campaign without acceleration (100,000 first doses/day).

Finally, Ong et al. [66] reported on a composite measure of disease severity, defined by a composite outcome of oxygen requirement, ICU admission, and death, and found that Delta was associated with increased disease severity compared to non-VOC (unadjusted OR 5.55 (95% 1.66 – 34.44); adjusted OR 4.90 (95%CI 1.43 – 30.78)). No difference was found for Alpha or Gamma.

One modeling study reported on adjusting Personal Protective Equipment (PPE) procedures. Pham et al. [81] modeled the impact of different interventions on transmission, healthcare worker (HCW) absenteeism, and test positivity as markers of intervention efficiency against Alpha transmission. In the baseline scenario, it was assumed that HCWs were using PPE while in COVID wards when seeing patients but not during breaks or when in other parts of the hospital, assuming 95% of HCWs worked in the same wards over time. While specific PPE used was not defined, PPE efficiency was defined as percentage reduction of droplet transfer. Assuming 90% effective PPE use in COVID wards, they found that extending PPE use to non-COVID wards (all HCWs used PPE with 90% effectiveness when on ward) would prevent 93.7% of all transmissions and would also prevent outbreaks among patients and HCWs. Even if PPE effectiveness was reduced to 70%, findings did not change significantly; however, if it was reduced to 50% or below, screening HCWs every 3 days was more effective than PPE use in all wards. Overall, PPE use in all wards was modeled to be more effective than all other interventions.

One observational study found that the amount of disposable plastic generated by a single RT-PCR diagnostic test and the PPE used by PCR operators was 821.8 g [82]. Given the increased testing with greater spread of COVID-19 due to VOC, the authors argue that there needs to be greater attention paid to biomedical plastic waste to minimize the environmental impact.

No studies had reported on this outcome as of September 27, 2021.

No studies had reported on this outcome as of September 27, 2021.

One study reported on the presence of SaRS-CoV-2 on regularly-touched environmental surfaces during high Alpha prevalence [82]. In shared spaces/surface contamination, patient bed handles, the nursing station, the reception desk, door handles of doctor’s office, toilet door handles, cell phones, patient toilet sinks, toilet bowls, and patient pillows (defined as high-touch surfaces) were considered as high-risk sources of transmission. Alcohol-based rubs (ethanol 70%) were effective at reducing the presence of SARs-CoV-2 on most surfaces after 15 min where sodium hypochlorite (0.001%) was mostly ineffective [82].

While this rapid review has several strengths, there are limitations that must be acknowledged. First, due to the rapid production of the literature on COVID-19 and VOC, 42% of the studies included in this review were preprints and have thus not yet undergone peer review. Nevertheless, most studies scored medium or high in the quality appraisal, suggesting that the evidence in this area is relatively reliable. Most studies used large health administrative databases as sources of evidence with reliable methods for determining exposures/outcomes. Additionally, our search strategy was limited to articles that specified reporting on one of the recognized VOC (Alpha, Beta, Gamma, and Delta). Given the growing trend that VOC are replacing the wild-type as the dominant strain as well as the continued emergence of other variants of interest, future consideration of expanding the search strategy may be warranted. It is also important to acknowledge the limitation of the epidemiology contact. Due to the variation in testing strategies in countries where studies occurred, the adequacy of case finding in the community and thus denominator completeness may vary, which impacts the ability to assess hospital rates and the impact of VOC on health system impacts and mortality. Finally, some studies reported mixed findings based on adjusted and unadjusted analyses, which must be considered when comparing across studies.