The number of worldwide cases of SARS-CoV-2 edged passed 100,000 on 6 March 2020, having been officially identified two months earlier, on 7 January. It took 12 days for the second 100,000 cases, only three days for the third 100,000 cases. Cases jumped to 400,000 just three days after that1. The WHO has acknowledged that the pandemic is accelerating. Efforts to contain the novel coronavirus have failed. The virus escaped China before it had even been identified and though increasingly draconian social distancing policies have been installed throughout the world, cases continue to rise.
Therefore, the attention of public health organisations has focused to antiviral therapies and a vaccine to reduce mortality and prevent further massive spread, respectively. Chinese researchers rapidly sequenced the novel coronavirus and shared it with the world2. This allowed laboratories to synthesise the virus and investigate just how it infects humans.
Viral culture experiments have revealed that SARS-CoV-2 is highly similar to the coronavirus that caused the Severe Acute Respiratory Syndrome (SARS) outbreak in China in 2002-2004 and the ongoing epidemic of Middle East Respiratory Syndrome (MERS) in the Middle East, which began in 2012. Indeed, at first glance the viruses could all be confused for each other. The virus consists of a coil of ribonucleic acid (RNA) which – like human DNA – encodes instructions for making more viruses, encompassed in an envelope covered in spikes. These spikes allow the virus to gain entry to lung cells by attaching to specific receptors on their surface. Once the virus has gained entry, the RNA is released and the human cell’s own machinery is hijacked to produce hundreds, sometimes thousands, of new viruses.
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Our immune system aims to both neutralise viruses before they gain entry to our cells and to destroy any cells that display signs of infection. Novel viruses like SARS-CoV-2 can spread rapidly through a population because nobody’s immune system has been primed to recognise and destroy the virus. In this case, the only way to bolster the body’s ability to fight the virus is by inoculating the population with a vaccine.
All vaccines work in essentially the same way – they show the immune system a specific part of a pathogen, known as an antigen, to the immune system. The immune system then mounts a controlled response against the antigen and produces antibodies. The immune system then stores the structure of the viral antigen and how to make the appropriate antibodies in a memory bank, allowing the body to fight the virus faster and more effectively. Traditionally, vaccines are made of either a live, weakened form of virus – called an attenuated virus – or a version that has lost its ability to infect cells through treatment with heat or chemicals. Increasingly, though, new vaccines are more technologically advanced. One approach involves splicing viral genes into the genome of bacteria. These transgenic bacteria, known as ‘recombinant vaccines’, act as antigen factories, mass-producing huge amounts of viral proteins. Other approaches involve directly inoculating humans with viral DNA or RNA, generating an immune response against the viral genome before it has ever entered the body.
So, if there are so many different vaccine technologies, why are researchers claiming it will take roughly 18 months to produce one? The answer lies in the clinical trials that need to be undertaken to ensure that vaccine candidates are effective and safe. Clinical trials are a mandatory phase of vaccine production, which must be forensically carried out to the letter of the law before regulatory approval. Trials normally happen in three main stages. Phase I determines whether the vaccine can find its way to the right part of the body to be effective and is broadly safe. Phase II widens the initial trial and attempts to demonstrate that an effective immune response is generated in a large group of people. Phase III is the largest, and longest, stage and identifies potential hazards and demonstrates value compared with other available vaccines.
These phases cannot be rushed. Researchers cannot prove that their vaccine is effective and safe if their clinical trials last mere weeks. Each phase involves a larger number of participants and investigates more vaccine characteristics than the last. Taken together, the clinical trial phase of vaccine development takes years, not months.
Donald Trump was recently given a reality check by his own health experts, who set out the most optimistic time-frame:
“So you’re talking over the next few months, you think you could have a vaccine?” Trump asked during a meeting with top health officials last week.
“You won’t have a vaccine,” corrected Health and Human Services Secretary Alex Azar. “You’ll have a vaccine to go into testing.”
“All right, so you’re talking within a year,” Trump said moments later.
“A year to a year and a half,” interjected Anthony Fauci, an expert in disease outbreaks, who has advised the last six administrations.
Even the 18 months outlined by Anthony Fauci is optimistic. It would, in the words of many researchers, be a record-breaker for a mass-produced vaccine. The two most promising candidates are being developed by Novavax, which is triumphing a recombinant vaccine, and Monderna, which has developed an RNA-based vaccine which entered clinical trials on 16 March3. Though early indications for the Moderna vaccine are promising, the clinical stages cannot be rushed. No RNA vaccine has ever been approved, so researchers can make no assumptions and take no shortcuts when determining its safety.
While the international response to the SARS-CoV-2 epidemic has been characterised by disjointed action taken by individual countries, laboratories across the world are working in collaboration to produce effective pharmaceutical interventions. A vaccine will not be ready to halt this phase of the pandemic in its tracks, but, if produced by the middle of next year, may play a vital role in limiting further epidemic outbreaks and prevent future deaths if the virus becomes endemic. Progress is made every day, but we cannot rely on pharmaceutical advances to end this pandemic. The only way we will do that is to simply do as we are told: wash our hands and distance ourselves from others.
