The MMR vaccine may protect some people against severe Covid-19, a study has claimed.
Scientists from the University of Georgia say the jab, which protects against measles, mumps and rubella, may also prevent people from catching the coronavirus.
No participant who was given the MMR jab as a child and had high levels of mumps antibodies in their blood got severe Covid-19, researchers said.
All children in the UK are offered the vaccine and around 91 per cent currently get immunised by their second birthday.
In the study, people with the highest levels of antibodies specific to mumps were ‘immune’ from Covid-19, the researchers claim. Antibodies are substances produced by the immune system to destroy invading viruses and bacteria.
The same effect was not seen for antibodies specific to measles or rubella, which are targeted by the same vaccine.
The participants had lived in close proximity to people sick with Covid-19 but never tested positive themselves, the researchers found.
The findings may explain why children only seem to get mild illness, if any at all, when they catch the coronavirus. The MMR jab is given to all infants from nine months old, and again before they are six years old, so the effects of it are still very fresh in their bodies.
This is not the first time the theory has been floated by scientists, who have also recognised continents with ‘measle-free status’, including Africa and Asia, have had fewer Covid-19 deaths.
A separate team at Cambridge University found key proteins in measles, mumps and rubella viruses have similarities with proteins on the surface of the coronavirus.
In theory, this would mean the body of a person vaccinated against MMR recognises the coronavirus when it invades, and can quickly mount an immune response.
The University of Georgia study found that people with the very highest levels of antibodies against mumps showed signs of immunity to the coronavirus, while severe illness was more likely among groups where mumps antibodies were low
After a number of researchers speculated that MMR is protective against Covid-19, researchers tested the theory on a group of 80 Americans.
The majority had tested positive for coronavirus, with their illnesses ranging from mild or no symptoms at all to requiring a ventilator in intensive care. Each person was given a score from 1 to 30 for the severity of their infection.
The group were split into 50 people who had been given the MMR jab as a child, and 30 who had not.
The researchers then compared levels of antibodies specific to mumps, measles and rubella among all the participants.
Antibodies are part of the immune system that help to clear an infection. They are produced either when a person is infected, or when they receive a vaccine, so that next time a virus comes along, the body is prepared to make antibodies specifically to fight it.
Therefore volunteers in the study had antibodies against the MMR either because they’d been vaccinated or previously exposed to the illnesses throughout life.
The main finding of the study was that those with a particularly strong mumps antibody response were less likely to suffer severe Covid-19.
But this was only seen in those whose antibodies came from vaccination, as opposed to those who had actually had the illness.
The researchers said this was probably because ‘the underlying antibodies that may protect against Covid-19 may have waned beyond protective levels’.
COULD THE MMR JAB PROTECT AGAINST COVID-19?
Scientists have been discussing whether the MMR jab offers some kind of protection against Covid-19 based on a number of observations.
In April, experts from the University of Cambridge analysed the structures of the MMR illnesses – measles, mumps and rubella – and the coronavirus in order to see if there were any similarities.
They found some unexpected similarities between proteins on the coronavirus surface and those of measles, mumps and rubella.
In theory, this would mean an MMR-vaccinated person had ‘cross reactive’ protection against Covid-19. If their body recognises proteins on the coronavirus, having seen similar ones from the MMR vaccine, they may be able to mount a response quickly.
But this has not been proven and its too early to say if this is the case.
Writing in the study before it was peer-reviewed, the researchers said: ‘We hypothesise that MMR could protect against poor outcome in Covid-19 infection.
‘We therefore propose that vaccination of at-risk age groups with an MMR vaccination merits further consideration as a time-appropriate and safe intervention.’
Some publications have suggested the BCG vaccine, which protects against tuberculosis and is given to those thought to be at risk of the disease, can also prevent Covid-19.
But Professor Adam Young and colleagues at Cambridge University said MMR jabs may be behind the effects, because vaccination levels of BCG and MMR are similar.
They also suggested that countries with high uptake of the MMR vaccine have been protected from severe Covid-19 outbreaks.
This was echoed by a paper from scientists in California, including from Stanford University, who said mass vaccination programmes in some countries may explain why countries have fared differently to the coronavirus.
Measles has been eradicated through extensive MMR vaccination programs in the western pacific region, as well as parts of Asia and across Africa, the team wrote.
By contrast, MMR vaccination programs have been problematic in the US, the rest of the Americas, and Europe – all of which have seen devastatingly high Covid-19 cases and deaths.
In Europe, measles is no longer considered eradicated in the UK, Albania, the Czech Republic or Greece. However, only the UK has been strongly hit by the pandemic.
In their paper, the team wrote: ‘While travel restrictions, control of congregate living conditions, and governmental interventions play roles in controlling the Covid-19 spread, it is possible that MMR vaccination programs are the basis for the huge international variation.’
A high level of antibodies against measles or rubella did not appear to offer ‘cross protection’ against Covid-19, despite previous studies suggesting this was the case.
Antibodies are measured in ‘titers’; the higher the titer level, the more someone is protected against a virus.
The results are given as arbitrary units per milliliter (AU/mL), with mumps titers scored between 0 and 300.
Every patient in the MMR vaccination group who had been hospitalised and required ventilation for Covid-19 had very low mumps titers – below 32 AU/ml.
Those with mild symptoms had a measurement of 134 AU/ml or below, while those who had no symptoms had the maximum titers of 134 to 300 AU/ml.
Ten people in the vaccinated group had not tested positive for coronavirus but had been in extreme close contact with a case with several days without the use of face masks or social distancing.
They were described as ‘functionally immune’, and had the highest antibodies of all study participants (average 172.4 AU/ml) suggesting they were completely protected from the virus.
Lead author of the study, Jeffrey E. Gold, president of World Organization, in Watkinsville, said: ‘This adds to other associations demonstrating that the MMR vaccine may be protective against Covid-19.
‘It also may explain why children have a much lower Covid-19 case rate than adults, as well as a much lower death rate.
‘The majority of children get their first MMR vaccination around 12 to 15 months of age and a second one from four to six years of age.’
Antibodies fade over time but can still offer protection against viruses.
The researchers worked out that a child has mumps antibodies below 134 AU/ml by the age of 14 years. It’s this same age that coronavirus prevalence increases sharply, they said.
In the US, there have been 65 per cent more Covid-19 cases diagnosed in babies under one years old compared to those over the age of two, which may be related to the fact infants get their first MMR dose at 12 months, it was claimed.
Co-author Dr David J. Hurley, professor and molecular microbiologist at the University of Georgia, said: ‘This is the first immunological study to evaluate the relationship between the MMR II vaccine and Covid-19.
‘The statistically significant inverse correlation between mumps titers and Covid-19 indicates that there is a relationship involved that warrants further investigation.
‘The MMR II vaccine is considered a safe vaccine with very few side effects. If it has the ultimate benefit of preventing infection from COVID-19, preventing the spread of COVID-19, reducing the severity of it, or a combination of any or all of those, it is a very high reward low risk ratio intervention.’
Dr Hurley suggested adults over the age of 40 should be given the MMR jab if they have never had it, regardless of whether or not they still have antibodies against the illnesses.
‘It would be prudent to vaccinate those over 40,’ he said.
The average age of those in the vaccination group of the study was much younger than those in the non-vaccinated group – 30 years compared with 57.
This may have skewed the results, given that age is the strongest risk factor for Covid-19 severity.
But the researchers suggested they could not get around this, considering those who have not had the MMR vaccine tend to be older because the triple jab was not introduced until the early 1970s.
They write in their paper: ‘Age differentiation was the only way to accurately separate people who definitively had prior MMR II vaccinations from those who had not.’
It’s not the first time scientists have proposed vaccinating vulnerable people with the MMR jab in order to shield them from Covid-19.
A team at Cambridge University found in April that part of the coronavirus’s structure is similar to mumps, measles and rubella.
Although it is unproven, this suggests the coronavirus will not be totally unfamiliar to to the body of someone with the MMR vaccine, and they would be able to rapidly mount an immune response.
Writing in their paper, the team said: ‘We therefore propose that vaccination of “at risk” age groups with an MMR vaccination merits further consideration as a time appropriate and safe intervention.’
They also suggested that Europe, the US and Americas have suffered greatly in the Covid-19 pandemic because it has been harder to drive MMR vaccine uptake.
MMR vaccine uptake is below the 95 per cent that health experts say is required for herd immunity in the UK.
But last year the proportion receiving their first dose in England increased to 90.6 per cent, after a peak of 92.7 per cent in 2013/14.
Two doses of the vaccine are required to ensure full protection from measles and coverage at five years was 94.5 per cent in 2019, the same as the previous year.