Coronavirus Update: Large Study Boosts Case For Vaccine Mixing
Plus, Japan Plans New Vaccine Funding
Executive Summary
Results from a large Swedish study provide further evidence that mixing different COVID-19 vaccines boosts effectiveness. Meanwhile, Japan plans new funding to support the home-grown development of coronavirus and other vaccines.
Heterologous Vaccine Boosting Improves Effectiveness, Study Says
A large-scale study in Sweden has shown that the use of heterologous vaccination with AstraZeneca PLC’s ChAdOx1 COVID-19 vaccine, followed by mRNA prime-boost vaccination, has higher effectiveness against risk of infection than homologous vaccination with just the AZ vaccine.
Earlier studies on mixing-and-matching vaccines demonstrated the heterologous prime-boost approach has generated a robust immune response, but this study shows the extent to which the strategy could reduce the risk of clinical infection. (Also see "Ex-Hilleman CEO On COVID-19 Vaccine Heterologous Boosting, Endemic Disease" - Scrip, 28 Sep, 2021.)
Conducted among nearly 541,071 subjects who received two doses against COVID-19 in Sweden until 5 July 2021, the study by Peter Nordstrom, Marcel Ballin and Anna Nordstrom from the Umea University in Sweden and UiT The Arctic University of Norway considered data from 94,569 who received ChAdOx1 followed by Pfizer Inc./BioNTech SE’s BNT162b2 prime-boost and 16,402 individuals who were administered ChAdOx1 and Moderna, Inc.’s mRNA-1273.
The study cohorts also included 430,100 individuals who received two doses of ChAdOx1 (homologous vaccination group) and 180,716 individuals who were unvaccinated.
During a mean follow-up time of 76 (range 1-183) days, symptomatic COVID-19 infection was confirmed in 187 individuals with heterologous vaccine schedules (incidence rate: 2.0/100,000 person-days) and in 306 individuals from the unvaccinated control group (incidence rate: 7.1/100,000 person-days).
Adjusted vaccine effectiveness was 67% (95% CI, 59-73, P<0.001) for the heterologous AZ/Pfizer combination and 79% (95% CI, 62-88, P<0.001) for the AZ/Moderna prime-boost vaccination. This compared with 50% effectiveness for homologous AZ vaccination (95% CI, 41-58, P<0.001).
When combined and analyzed together, the two heterologous vaccine schedules had an effectiveness of 68% (95% CI, 61-74, P<0.001), the study which was published in The Lancet Regional Health - Europe journal on 17 October said.
The use of heterologous vaccine schedules appears to be an effective alternative for increasing population immunity against COVID-19, including against the Delta variant which dominated the confirmed cases during the study period, the research paper concluded. The number of COVID-19 cases severe enough to result in inpatient hospitalisation was too low for the researchers to be able to calculate the effectiveness against this outcome.
These findings could have important implications for vaccination strategies evolved by various countries, particularly against the backdrop of insufficient supplies and adverse reactions.
Japan Proposes New Vaccine Support Plan
The government of Japan’s new prime minister Fumio Kishida is reported to be drawing up a broad economic package that includes a proposed dedicated JPY500bn ($4.39bn) fund to support the development of vaccines and new drugs for infectious diseases.
The plan, widely reported in Japanese media but not yet officially announced, would form part of plans also intended to strengthen R&D activities around both vaccines and other treatments for COVID-19.
While work is underway at several firms, Japan has lagged in the development of home-grown coronavirus vaccines, attributed to a range of factors, including previous government policy de-emphasis and historic public concerns over side-effects. (Also see "Pharma Power Japan Barely In COVID Vaccines Race. Why?" - Scrip, 16 Dec, 2020.)
As a result, the country is currently relying totally on vaccines developed elsewhere in its national COVID-19 inoculation program, mostly Moderna, Inc. and Pfizer Inc.’s mRNA vaccines and to a lesser extent AstraZeneca PLC’s jab.
Kishida, who assumed the position on 4 October, has indicated he supports increased funding for academic science and technology initiatives in general, and before being elected had called for a new agency to oversee government responses to public health emergencies.
While Japan took similar steps in 2015 with the establishment of the Agency for Medical Research and Development (AMED) to better coordinate government policies, programs and funding across multiple ministries, there is uncertainty whether the prime minister’s idea will come to fruition.
Similar steps are being taken in neighboring South Korea to support vaccine development and the state response to infectious diseases. (Also see "Korea Kick-Starts Major Consortium For Next-Gen mRNA Vaccines" - Scrip, 1 Jul, 2021.)
Kishida’s overall economic package is expected to be finalized around the end of this month.