Another blog on Covid-19 for the non-expert
The three most commonly quoted reasons I’ve seen for vaccine pessimism are: (1) vaccines take many years to make, the mumps vaccine took four years. (2) We still don’t have an effective vaccine against HIV and (3) we still don’t have any vaccines against SARS and MERS.
All three points are correct but only superficially, and so let’s look under the surface and put the claims into more detailed context.
Scientists isolated the mumps virus in 1945 and the first vaccine appeared in 1948, although its effectiveness was short term. The Jeryl Lynn vaccine was launched in 1967 in the United States and entered routine use in 1977. The mumps vaccine therefore took between three years or 22-years to develop, depending upon how you look at it. The problem with comparing Covid-19 to mumps however, is the year the first mumps vaccine appeared, 1967, was 53-years ago. At that time there was only one way to make a vaccine and that was from the virus itself. It was necessary to isolate the virus, then inactivate it so it remained potent to the immune system but non-pathogenic (known as an attenuated vaccine). Things have come a very long way since 1967. Nowadays we no longer need the virus itself, but only its genetic sequence (RNA in the case of Covid-19).
Covid-19 was first reported in December 2019, and by February 2020 the 26,000 – 32,000 RNA code sequence of SARS-COV-2 (the Covid-19 virus) went round the world via the internet. Genetic sequencing and the internet were both science fiction in 1967; in fact the structure of DNA was only elucidated 14-years before. Vaccine development today is another world, and comparing a Covid-19 vaccine to one for mumps is like saying electric cars are impossible because there weren’t any in the 1960s.
HIV was first identified as the causative virus for AIDS in 1984 and despite some trials, no effective vaccine has emerged. HIV however, is an entirely different virus and if SARS-CoV-2 was anything like HIV, few scientists would be optimistic of ever getting a vaccine. HIV attacks the immune system, the very thing a vaccine stimulates in the fight against infection. HIV also mutates rapidly, and it’s ability to mutate appears to be built into its very biochemistry because a key enzyme in its reproduction (reverse transcriptase) cannot translate its genetic code accurately. This has led to over 60 strains of HIV virus world-wide. SARS-CoV-2 is far more stable and all evidence suggests it does not attack the immune system. Comparing HIV and SARS-CoV-2 regarding a vaccine is like saying I can’t rid my lawn of dandelions because I can’t eliminate Japanese knotweed.
There was an outbreak of SARs in 2003 and MERS in 2012. The reason why no vaccine has emerged for these viruses is less technical than for HIV – no one has really tried. There was an initial effort and there are vaccine candidates, but it soon became clear that neither of these diseases turned out to be the deadly pandemics they were first thought to be. They were successfully contained and haven’t been seen for several years.
By far the biggest difference between attempts at a Covid-19 vaccine and any other are the enormous international collaborative efforts currently taking place. There are an estimated 100 Covid-19 vaccines somewhere in development as well as other possible treatments such as a range of drugs, both established and new, including antibody-type treatments which proved successful against Ebola. (Remdesivir was aimed at Ebola but was succeeded by antibody-type drugs. Remdesivir is now being tested against Covid-19). At the leading edge of fresh approaches is research into RNAi. (Richard Jorgensen discovered RNAi, after he became curious about patches of colour on petunia petals. His investigations led to the discovery of a whole new branch of genetics and won him the Nobel Prize in 2006).
We have to be realistic about the possibility and timing of a vaccine, or other treatment, and it may turn out no such vaccine emerges, or if it does, it might be years away. The honest answer is we don’t know but I do believe there are reasons to be optimistic. The Jenner for example are entering Phase II and III trials after promising phase I results. But in the meantime, if a more pessimistic climate arises, then at least let’s make sure it’s for the right reasons and not some spurious comparisons.