Jan. 26 2021

With Vaccine Supply Limited, Older New Yorkers Should Get Priority: Study

Data modeling projections: giving older adults priority access to vaccines would reduce more hospitalizations and deaths; delaying second doses would provide potentially larger benefits

New York City residents age 65 and older should be prioritized within phase 1b of the COVID-19 vaccine roll-out so as to minimize the overall number of severe infections, hospitalizations, and deaths in the city, according to new research. Data modeling projections by Columbia University Mailman School of Public Health researchers find similar benefits for extending the time between first and second doses for all vaccine recipients, in case infection rates climb and/or vaccine supplies run low. The findings are published on the pre-print server medRxiv ahead of peer review.

Vaccination is critical for mitigating COVID-19, especially if the more infectious SARS-CoV-2 variants supplant currently circulating variants. If that happens, timely vaccination could prevent 15,598 hospitalizations and 2,598 deaths in New York City over the next six months compared to no vaccination. Further, prioritizing seniors ahead of grocery workers, firefighters, police officers, teachers, transit workers, and others in phase 1b could prevent 645 additional hospitalizations and 129 additional deaths than a policy not prioritizing seniors in phase 1b. Importantly, all these analyses assume the city continues current public health interventions in the coming months, even with the vaccine rollouts.

“To avert unnecessary hospitalizations and deaths, we need to vaccinate individuals age 65 or older as soon as possible,” says lead author Wan Yang, PhD, assistant professor in the Department of Epidemiology. “Right now, seniors have to compete with everyone else approved for vaccination and, as a result, they may not get vaccinated soon enough to be protected from COVID.”

It is also important that the city balance giving prioritization to groups that need the vaccine the most while getting the vaccines it has into arms so as to avoid bottlenecks, the researchers say. While seniors would be given priority within 1b in the study’s scenario, available vaccine doses should be given to the next priority groups as soon as possible without awaiting hesitant up-stream groups. Giving priority to seniors would not affect healthcare workers and others in group 1a, most of whom are already vaccinated. Currently, New York City and New York state follow U.S. Centers for Disease Control and Prevention guidelines on vaccine prioritization.

Delaying Second Dose Could Stretch Supply

Delaying the second vaccine dose by an additional four weeks beyond the current three-week interval would substantially increase the number of people receiving the first dose of vaccine, in dire situations where new more virulent virus variants lead to substantial increases in infections, hospitalizations, and deaths, and/or when there are vaccine shortages. Immunity after the first dose of the Pfizer-BioNTech or Moderna vaccine is estimated at 90 percent and 95 percent after the second dose, although the researchers say the efficacy of vaccination off-protocol is unknown. (To account for a potential dip in immunity in the extended time between first and second doses, the scientists calculated their results using 85 percent efficacy after the first dose.)

In a variety of scenarios they tested, including with and without the U.K. virus variant dominant and at varying rates of vaccine hesitancy, they consistently found that a delay in the second vaccine dose could further prevent as many as 4,284 hospitalizations and 872 deaths in New York City over the next six months compared to the three-week-apart vaccination regimen. Currently, the United Kingdom has delayed second doses to three months after the first dose, as it faces a spike in cases related to a more virulent variant of the virus.

“If vaccines are widely available and the city can vaccinate people as quickly as possible without capacity limits, then the dosing regimen as recommended by the manufacturers should be strictly followed. But right now, we don’t have enough vaccines nor the capacity in many places. In addition, there are the more infectious new variants emerging, which may make things worse. It is a race against new infections and the new variants,” says Yang.

Delay Vaccination for People with Immunity?

For individuals with recent infection, immediate vaccination may provide little additional protection. The researchers looked at whether delaying vaccination for these individuals could free up available vaccine doses to others with greater need. They found that pre-testing individuals for antibodies to SARS-CoV-2 can contribute to small reductions in infections, hospitalizations, and deaths. The estimated impact is only a 2 percent reduction, although the researchers say this is likely an underestimate of the benefit of pre-testing.

Future Outlook

If the current SARS-CoV-2 variant remains dominant, projections show the epidemic would decline in the coming weeks, with a 6-9 percent reduction in infections, hospitalizations, and deaths due to mass vaccination over the next six months, across all scenarios. However, if the new variant becomes dominant over the next four weeks, the city will likely see substantial increases in infections and related health outcomes. If this happens, mass vaccination is critical and will result in a 26-52 percent reduction in infections, hospitalizations, and deaths in New York City, compared to no vaccination. The researchers assume 300,000 people are vaccinated every week, although they acknowledge that this number could be higher or lower.

Study co-authors include Jeffrey Shaman (senior author) and Sasikiran Kandula, both in the Department of Environmental Health Sciences at Columbia Mailman School. Shaman and Columbia University disclose partial ownership of SK Analytics, a provider of influenza forecasting and analytics services. Shaman discloses consulting for Business Networking International. Other authors have nothing to disclose.

This study was supported by the National Institute of Allergy and Infectious Diseases (AI145883), the National Science Foundation Rapid Response Research Program (RAPID; 2027369), and the NYC Department of Health and Mental Hygiene (DOHMH).