Why experts think MMR jab may save adults from Covid
Childhood vaccine at heart of dramatic new trial
THINK of the measles, mumps and rubella (MMR) jab and one image might spring to mind — a mother cradling an infant as a nurse injects the potentially life-saving vaccine into their arm.
It could soon be the mother receiving the vaccine too — to protect against Covid-19.
Some evidence suggests the triple jab, given to millions of Irish children, could be a powerful weapon in the battle against coronavirus, either by protecting adults against infection, or reducing symptoms.
That was certainly the thinking behind the decision by Dr Martin Scurr, the Mail’s GP columnist, to have the MMR jab — to ‘ginger up’ his immunity, as he explained in Good Health last week.
The protective potential of MMR hit the headlines when the crew of the US aircraft carrier USS Theodore Roosevelt was struck by a Covid-19 outbreak.
More than 1,100 sailors on board tested positive, yet just one needed hospital treatment, (and later died) according to a report published last month in the journal mBio.
Even allowing for the likelihood that many were young and fit, researchers calculated it would still be expected that about 14 per cent (over 150 in this case) would need to be hospitalised.
But the sailors all had one thing in common; as new recruits mostly in their late teens or 20s, each had been given the MMR vaccine, in line with US military policy.
Some scientists think the jab may have protected many crew members against serious illness and could also explain why so few children develop symptoms from Covid-19. In Ireland, children make up less than two per cent of confirmed cases.
Between 80 and 90 per cent of all Irish children, teenagers and young adults have had the MMR jab, their first dose aged one, and a booster, at three years.
NOW the idea that the readily available and relatively cheap vaccine could be used to protect millions of adults against Covid-19 is attracting wider interest.
Last month, doctors at the Kasr El Aini Hospital in Cairo, Egypt, began recruiting up to 200 doctors, nurses and carers on the coronavirus frontline to see if giving them the MMR vaccine protects them against severe coronavirus symptoms.
The trial — which will run until October — is the first of its kind.
But how might a vaccine against common childhood illnesses tackle the virus?
Most of the 100 or so Covid-19 vaccine trials under way worldwide focus on specific targets unique to the virus itself, and are made either with traces of the ‘spike’ protein found on the surface of the virus, or fragments of its genetic material. The idea is the immune system recognises the virus material in the vaccines as foreign and creates infection-fighting cells (antibodies and T cells) should it then encounter Covid-19.
In other words, they are designed to work against Covid19 and nothing else.
The same applies to most infectious disease vaccines. But a small group of vaccines, including the MMR, the BCG jab given to protect against tuberculosis (TB) and the oral version of the polio vaccine, are different.
These are made with ‘live’ but massively weakened versions of the viruses or bacteria (in the case of the BCG) themselves.
As well as priming the immune system to produce diseasefighting cells that target the infectious organism, live vaccines pep up the whole immune system so it’s more alert to any invading organisms.
It’s thought this is because the presence of any live virus or bacterium is enough to put the whole immune system on alert.
‘It’s a bit like an army putting all its snipers on duty, ready to take out anything that is a potential threat,’ explains Eleanor Riley, a professor of immunology and infectious diseases at Edinburgh University.
As we reported in March, there are several trials under way globally to see if the BCG jab can soften the blow of Covid-19.
Last week a study found that the BCG vaccine, that was given to teenagers in this country from 1953 until 2005 to protect against TB, may protect against coronavirus. The study, published in the Proceedings of the National Academy Of Sciences, compared the jab’s popularity in a country with their rate of infection and death.
The vaccine has previously been found to combat infectious diseases other than TB. A study, published in The BMJ in 2016, found that babies given the BCG jab were 30 per cent less likely to die of any infectious disease in their first year.
News that the jab might also protect people against coronavirus has led to shortages in some parts of the world. Doctors in Japan said they were running out of BCG as so many adults were paying privately to be immunised as protection against Covid-19. But when it comes to MMR, there could be another reason why the vaccine buffers the effects of Covid-19, say University of Cambridge scientists.
They studied blood samples of British patients treated in the early stages of the pandemic — the antibodies made by their immune system were similar in structure to antibodies produced in response to rubella (German measles), one of three viruses targeted by the MMR vaccine.
The Cambridge team believes the rubella antibodies triggered by the vaccine may be seeing off the coronavirus before it does too much damage.
In a paper online (but not yet published in a peer-reviewed journal), the scientists wrote: ‘If there is a link, we propose that vaccination of “at risk” age groups with an MMR vaccination should be considered.
‘To create a Covid-19 vaccine will be arduous and may require time which we cannot afford.’
But some experts warn against giving the MMR jab without stronger evidence.
There is ‘a good chance’ this effect on the immune system is short-lived in some people — days, rather than weeks, months or years, says Professor Riley.
‘It’s also likely that if as an adult or even as a child your immune system has ever come into contact with measles, mumps or rubella in the past, it will not respond as vigorously to another vaccine. There is no good reason for anyone to pay for a private MMR or indeed BCG vaccine in the hope of avoiding Covid-19.’