Affordable SARS-CoV-2 protein vaccines for the pandemic endgame

The astonishing speed with which coronavirus disease 2019 (COVID-19) vaccines were developed is nothing short of a scientific triumph. Their rapid development was in part enabled by the use of novel gene-delivery technologies that could be manufactured quickly and at scale 1 . Both the mRNA (e.g. BNT162b2, mRNA-1273) and adenovirus-based vaccines (e.g. ChAdOx-1 nCov-19, Ad26.COV2.S) deliver genetic material to cells to instruct the production of the SARS-CoV-2 spike protein. These vaccines have saved many lives, with estimates of vaccination averting at least 1 million deaths within the USA alone 2 . While the use of these new vaccine technologies in high-income countries (HICs) has dramatically reduced the number of COVID-19-related hospitalisations and deaths, vaccination rates in low- and middle-income countries (LMICs) remain concerningly low. For example, as of May 8, 2022, only 17% of the eligible population in Africa have received two vaccine doses 3 . Vaccine coverage in LMICs has relied on ‘traditional’ technology approaches, namely inactivated viral vaccines. The CoronaVac (Sinovac), BBIBP-CorV (Sinopharm) and COVAXIN (Bharat Biotech) comprise around half of all vaccines delivered globally and have played an important role in controlling COVID-19 in LMICs 4 . Unlike mRNA vaccines, inactivated vaccines do not require long-term storage at very low temperatures, thus facilitating their use in LMICs. However, a limitation of these vaccines is the reduced capacity to neutralise infection with the Omicron variant, particularly in the absence of any additional booster dose after the initial vaccine course 5 . Disparities in vaccine access further compound this problem. Administration of booster doses in HICs has been prioritised over equitable vaccine distribution, thereby impacting effective control of global COVID-19 infections, deaths and emergence of new variants. Mechanisms to distribute vaccines to LMICs have also faced serious problems. The COVID-19 Vaccines Global Access Scheme (COVAX) was established to facilitate global COVID-19 vaccine distribution; however, COVAX is underfunded, has struggled to secure enough vaccine doses and has failed to meet many key targets. It is clear that global vaccine production and supply need to be increased, ideally through the building of vaccine manufacturing and distribution capacity in LMICs.