Developing vaccines at speed

In just under nine months, vaccines for COVID-19 were developed, tested in clinical trials, reviewed, and approved for emergency use by regulators and are now being administered to millions of people worldwide.

A number of factors made this accelerated pace possible, while maintaining the same thorough testing and rigorous safety standards as for any other medicine or vaccine.

When did coronavirus vaccine development start?

Pandemic planning started years ago

Experts had been preparing for a possible, viral pandemic for years. Without knowing exactly what might cause an outbreak, there was already ongoing research to advance scientific understanding and strategies in place to move quickly to develop a vaccine in the shortest possible time should a new virus of concern emerge.

Coronaviruses were already well understood

When the SARS-CoV-2 virus emerged, scientists already understood a lot about the ‘coronavirus family’. Coronaviruses have been around for many years and they have tried to jump from animals to humans before too, including the SARS coronavirus in 2002 and MERS coronavirus in 2012.2

This meant that scientists weren’t starting from scratch – they already knew a little about coronavirus biology, how the SARS-CoV-2 virus might spread and how to target it with a vaccine.

Vaccine development technology already existed

Fortunately, the technology and ‘platforms’ that allowed scientists to develop vaccines quickly already existed and were already tested in humans before the COVID-19 pandemic began.3

Vaccine platforms such as ‘viral vectors’ and ‘mRNA’ had been studied for many years. Viral vector vaccines had already been tested in clinical research for Ebola4, prostate cancer5, MERS2, malaria, tuberculosis, and influenza6 and have consistently shown to be effective with acceptable safety profiles. This research, combined with a wealth of documented experience with different vaccines in humans, meant the COVID-19 vaccines could be advanced quickly into clinical trials based on what was already known.

Advances in genetic engineering also meant that vaccines could be developed rapidly and precisely once the genetic code for COVID-19 was known. Researchers successfully identified and shared the genetic code approximately eight days after the first reported cluster of pneumonia cases in Wuhan, China.7

Clinical trials were conducted quickly but without shortcuts

Clinical trials were designed globally in consultation with international regulators that met the criteria for emergency use approval, should results prove positive. As with all clinical development the highest standards of both safety and ethics were upheld throughout the development process, following the principles developed by world health and regulatory organisations. Independent Data and Safety Monitoring Boards have overseen the clinical trials to ensure safety and quality standards were met.

Many thousands of people also helped by quickly volunteering for clinical trials. Due to public interest, these trials enrolled participants much faster than normal. The trial period was also relatively short for key data readouts which meant it didn’t take long to establish that the vaccines worked. No shortcuts were taken in terms of trial quality or safety.

Independent regulators allowed real-time review of evidence

Independent regulators – such as the European Medicines Agency (EMA), the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) and the U.S. Food and Drug Administration (FDA) – review the safety and efficacy of medicines and vaccines before they’re approved.

Given COVID-19 was deemed a public health emergency, many regulators pivoted from their standard review and approval process and allowed real-time or “rolling reviews” of vaccine evidence from trials. This meant that all data on vaccine efficacy, safety and quality was assessed as it became available, rather than it being submitted and reviewed once a study had completed. This process is much faster, but without compromising approval standards.

Pharmacovigilance (safety monitoring) procedures are also in place for all COVID-19 vaccines, with thorough scrutiny from regulators, pharmaceutical companies, scientific and medical experts to allow appropriate use of vaccines in the real world. The standard of testing and monitoring is actually higher than for most other medicines, as vaccines are generally administered to healthy people.8

Global collaboration at speed

The impact of global collaboration to identify and develop strategies to overcome the pandemic cannot be underestimated. Researchers, doctors, scientists, approval boards, regulatory groups, governments, manufacturers (and more) mobilised quickly with everyone working hard and fast to make vaccines available as soon as possible, while maintaining the same high standards and quality expected of any medicine.

The real-world evidence starting to emerge for these vaccines affirms that this approach has contributed to reducing the burden of illness from COVID-19 and to saving lives.9


1. Plotkin S, Orenstein W, Offit P, et al. Plotkin's Vaccines. 7th Edition. 2017.

2. Folegatti PM, Bittaye M, Flaxman A, et al. Safety and immunogenicity of a candidate Middle East respiratory syndrome coronavirus viral-vectored vaccine: a dose-escalation, open-label, non-randomised, uncontrolled, phase 1 trial. Lancet Infect Dis. 2020;20 (7): 816-826. doi: 10.1016/S1473-3099(20)30160-2. Epub 2020 Apr 21. Erratum in: Lancet Infect Dis. 2020 May 12; Erratum in: Lancet Infect Dis. 2020 Jun 8; PMID: 32325038; PMCID: PMC7172901.

3. Sempowski GD, Saunders KO, Acharya P, et al. Pandemic Preparedness: Developing Vaccines and Therapeutic Antibodies For COVID-19. Cell. 2020;181(7):1458-1463.

4. Monath TP, Fast PE, Modjarrad K, et al. Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG). rVSVΔG-ZEBOV-GP (also designated V920) recombinant vesicular stomatitis virus pseudotyped with Ebola Zaire Glycoprotein: Standardized template with key considerations for a risk/benefit assessment. Vaccine X. 2019; 1: 100009.

5. Cappuccini F, Bryant R, Pollock E, et al. Safety and immunogenicity of novel 5T4 viral vectored vaccination regimens in early-stage prostate cancer: a phase I clinical trial. J Immunother Cancer. 2020; 8 (1): e000928.

6. Ewer KJ, Lambe T, Rollier CS, et al. Viral vectors as vaccine platforms: from immunogenicity to impact. Curr Opin Immunol. 2016; 41: 47-54.

7. World Health Organization. Archived: WHO Timeline - COVID-19. Available at Last accessed June 2021.

8. Vaccine Knowledge Project. How vaccines are tested, licensed and monitored. Available at Last accessed: June 2021.

9. GOV.UK COVID-19 vaccine surveillance report: 3 June 2021 (week 22). Available at Last accessed: June 2021.