Optimal SARS-CoV-2 vaccine allocation using real-time seroprevalence estimates in Rhode Island and Massachusetts

Abstract

As three SARS-CoV-2 vaccines come to market in Europe and North America in the winter of 2020-2021, distribution networks will be in a race against a major epidemiological wave of SARS-CoV-2 that began in autumn 2020. Rapid and optimized vaccine allocation is critical during this time. With 95% efficacy reported for two of the vaccines, near-term public health needs require that distribution is prioritized to the elderly, health-care workers, teachers, essential workers, and individuals with co-morbidities putting them at risk of severe clinical progression. Here, we evaluate various age-based vaccine distributions using a validated mathematical model based on current epidemic trends in Rhode Island and Massachusetts. We allow for varying waning efficacy of vaccine-induced immunity, as this has not yet been measured. We account for the fact that known COVID-positive cases may not be included in the first round of vaccination. And, we account for current age-specific immune patterns in both states. We find that allocating a substantial proportion (> 75%) of vaccine supply to individuals over the age of 70 is optimal in terms of reducing total cumulative deaths through mid-2021. As we do not explicitly model other high mortality groups, this result on vaccine allocation applies to all groups at high risk of mortality if infected. Our analysis confirms that for an easily transmissible respiratory virus, allocating a large majority of vaccinations to groups with the highest mortality risk is optimal. Our analysis assumes that health systems during winter 2020-2021 have equal staffing and capacity to previous phases of the SARS-CoV-2 epidemic; we do not consider the effects of understaffed hospitals or unvaccinated medical staff. Vaccinating only seronegative individuals avoids redundancy in vaccine use on individuals that may already be immune, and will result in 1% to 2% reductions in cumulative hospitalizations and deaths by mid-2021. Assuming high vaccination coverage (> 28%) and no major relaxations in distancing, masking, gathering size, or hygiene guidelines between now and spring 2021, our model predicts that a combination of vaccination and population immunity will lead to low or near-zero transmission levels by the second quarter of 2021.

The role of connectivity on COVID-19 preventive approaches

“…We observed that in the absence of susceptibility-based targeting, interventions prioritising highly connected individuals were more effective early in the epidemic. Others have highlighted the importance of antibody testing to prevent infection and death, [10, 18] and our results further support this approach especially when targeting highly connected individuals late in an epidemic when a high proportion has already been infected. The proportion of healthcare workers with SARS-CoV-2 antibodies ranges between 2-50% in different settings, [19] based on our results, targeting the available doses based on previous immunity could maximise its impact especially in settings where seroprevalence is high.…”

Prioritizing COVID-19 vaccination efforts and dose allocation within Madagascar

“…Given that Madagascar has now experienced multiple waves of infection (www.covid19mg.org) and that estimates of seroprevalence from blood donors in Madagascar show elevated population immunity [23], we also investigated strategies to take previous infection and thus immunity into account. Unsurprisingly, vaccinating only seronegative individuals allows for doses to be reallocated and expand protection to a larger population [8,26,27]. However, we note that assessing seropositivity via rapid testing at health facilities could slow the speed of vaccine delivery, which, in situations of high seropositivity, could reduce benefits in terms of mortality reductions.…”

Comparison of Different Covid-19 Vaccines Globally: An Overview

“…Serious side effects, such as allergic responses, have been recorded infrequently and no long-term consequences have been recorded [2,10]. The main outcomes of the trials will be monitored until August2021, while the secondary outcomes will be monitored until January 2023 Tran et al [11]. The vaccine was the first COVID-19 vaccine to be approved for emergency use by a strict regulatory authority [12] and the first to be licensed for routine use [13].…”

“…Pfizer and BioNTech intended to produce around 2.5 billion doses in 2021 as of March30, 2021 [5]. BioNTech and Pfizer have agreed to pay around $3 billion in advance purchase agreements to offer a licensed vaccine in the United States, the European Union, the United Kingdom, Japan, Canada, Peru, Singapore, and Mexico [11]. Because the vaccine must be maintained at extremely low temperatures, distribution and storage are logistical challenges.…”