Given the need to control current and emerging variants of concern that can evade the immune response to available vaccines and undermine their effectiveness, efforts are in progress to develop second-generation vaccines to protect against SARS-CoV-2 variants. What’s next for COVID-19 vaccine development? It is also possible that the apparent decline in vaccine effectiveness is due to the circulation of SARS-CoV-2 variants that, as a result of ongoing viral evolution, have acquired mutations in the spike protein that allow for the evasion of vaccine-induced immunity. However, breakthrough cases in vaccinated individuals have been reported and may account for the high numbers of infections recently recorded in Israel, a country that was successful in rapid roll out of COVID-19 vaccination and has achieved high coverage levels.1 These trends may reflect a possible waning in vaccine-induced immunity over time, which may call for the requirement for booster vaccinations. People who are fully vaccinated against COVID-19 are highly protected against severe infection, hospitalization and death. This triggers the production of antibodies against the virus that can prevent it from infecting host cells upon a subsequent infection. Several of the COVID-19 vaccines currently authorized for use work by instructing our own cells to make copies of the virus spike protein, which are recognized as being foreign by our immune systems. The key role of the spike protein in mediating viral entry into lung cells (through binding to the angiotensin-converting enzyme 2 receptor and subsequent virus-host membrane fusion) underpins its selection as the main target protein in COVID-19 vaccines. Most COVID-19 vaccines in use and in development are designed to elicit immune responses mediated by neutralizing antibodies against the SARS-CoV-2 spike protein. Limitations of current vaccines against COVID-19 Despite the success of current vaccines in mitigating the threat of severe disease from SARS-CoV-2 infection, there are some ongoing challenges, and the optimization of COVID-19 vaccines is an area of continuing research. The landscape of vaccine development has undergone rapid change in the global response to the pandemic, with the utilization of novel platforms to create new vaccines at an unprecedented speed. The accelerated development of vaccines against COVID-19 and their deployment in mass vaccination programmes has been a major public health achievement. The response to COVID-19 – a success story in vaccine development

Spike protein vaccine