Viral vector vaccines were also developed for the COVID‑19 pandemic after the technology was previously cleared for Ebola. Moderna began human testing of an mRNA vaccine in 2015. In contrast, mRNA is a molecule that can be made quickly, and research on mRNA to fight diseases was begun decades before the COVID‑19 pandemic by scientists such as Drew Weissman and Katalin Karikó, who tested on mice. Vaccines that use an inactive or weakened virus that has been grown in eggs typically take more than a decade to develop. As of March 2020, there was one (DNA-based) MERS vaccine which completed Phase I clinical trials in humans, and three others in progress, all being viral-vectored vaccines: two adenoviral-vectored (ChAdOx1-MERS, BVRS-GamVac) and one MVA-vectored (MVA-MERS-S). When MERS became prevalent, it was believed that existing SARS research might provide a useful template for developing vaccines and therapeutics against a MERS-CoV infection. There is also no proven vaccine against MERS. There is no cure or protective vaccine proven to be safe and effective against SARS in humans.
Vaccines against SARS and MERS have been tested in non-human animals.Īccording to studies published in 20, the identification and development of novel vaccines and medicines to treat SARS was a priority for governments and public health agencies around the world at that time. Previous projects to develop vaccines for viruses in the family Coronaviridae that affect humans have been aimed at severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). However, vaccines have been produced against several animal diseases caused by coronaviruses, including (as of 2003) infectious bronchitis virus in birds, canine coronavirus, and feline coronavirus. Prior to COVID‑19, a vaccine for an infectious disease had never been produced in less than several years – and no vaccine existed for preventing a coronavirus infection in humans. Ī US airman receiving a COVID‑19 vaccine, December 2020 By December 2020, more than 10 billion vaccine doses had been preordered by countries, with about half of the doses purchased by high-income countries comprising 14% of the world's population. Īs of 2 December 2021, 8.07 billion doses of COVID‑19 vaccines have been administered worldwide based on official reports from national public health agencies. Many countries have implemented phased distribution plans that prioritize those at highest risk of complications, such as the elderly, and those at high risk of exposure and transmission, such as healthcare workers. The COVID‑19 vaccines are widely credited for their role in reducing the severity and death caused by COVID‑19.
On 10 January 2020, the SARS-CoV-2 genetic sequence data was shared through GISAID, and by 19 March, the global pharmaceutical industry announced a major commitment to address COVID‑19. The initial focus of SARS-CoV-2 vaccines was on preventing symptomatic, often severe illness. This knowledge accelerated the development of various vaccine platforms during early 2020. Prior to the COVID‑19 pandemic, an established body of knowledge existed about the structure and function of coronaviruses causing diseases like severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). As the same person may receive more than one dose, the number of doses can be higher than the number of people in the population.Ī COVID‑19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the virus that causes coronavirus disease 2019 ( COVID‑19). For vaccines that require multiple doses, each individual dose is counted. COVID‑19 vaccine doses administered by continent as of Oct 11, 2021.
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