Why it may be years before there’s a vaccine for COVID-19

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The COVID-19 pandemic has impacted millions of people around the globe, prompting researchers to shift their focus to developing vaccines and treatments to prevent and slow the spread of the virus.

In fact, there are about 80 vaccines in preclinical and clinical evaluation according to the World Health Organization.

While these research efforts are encouraging, generally speaking, developing a vaccine is no easy feat. It’s critical to understand how well a vaccine protects from infection before it can be used in people. It’s equally important to make sure the vaccine doesn’t have any adverse effects. Both usually require extensive testing in animal models, which takes time.

What role do vaccines play to prevent disease? How can they stop an outbreak? 

Vaccines train our bodies to recognize pathogens when they infect us, and to respond faster to clear the infection. Outbreaks can be limited because vaccinated individuals will be less likely to transmit the infection to others.

How do vaccines work? 

The goal of most vaccines is to generate neutralizing antibodies that can bind to the pathogen and cause it to be removed from the infected tissue. 

There are several steps involved in the immune response:

  • When the vaccine is injected, professional antigen presenting cells, which serve as the security guards of the immune system, arrive at the site and phagocytose, or eat, the vaccine components and process them to present to T cells and B cells. 
  • T and B cells are then activated to produce cytokines and antibodies respectively, which then seek out and eliminate the infection.

How long does it typically take to develop a vaccine? 

This is a difficult question to answer. Generally, for a vaccine or drug, it can take as long as 10 to 12 years for a discovery in the lab to make it to patient use.

Internationally, compassionate use programs have allowed select vaccines to be tested in humans, but those results could be months or years away. 

Is it harder to develop a vaccine for the coronavirus family? If it’s developed, how long would immunity last? 

Coronaviruses don’t present any special challenges for vaccine development. The validation and testing process will be similar, and both take time. 

It’s not possible to predict how long the immunity will last. The longevity of the response varies for each type of vaccine and must be determined empirically.

Purnima Dubey is an associate professor of Microbial Infection and Immunity at The Ohio State University College of Medicine.