One of the consequences of the pandemic has been a decline in routine medical care and immunizations, so in November 2022 the World Health Organization declared measles an “imminent threat in all regions of the world.”
They described how in 2021 a record number of children (nearly 40 million) missed at least one dose of the measles vaccine.
Measles is a viral respiratory disease. This is similar to the transmission of the Corona virus, as it spreads between people through droplets and aerosols (airborne transmission). In mild cases, the infection causes a rash and fever.
But severe cases can include encephalitis (swelling of the brain), blindness, and pneumonia. About 9 million cases and 128,000 deaths are recorded annually. The measles vaccine, which can be given alone or in combination with other vaccines such as mumps and rubella, to immunize MMR is very effective.
Most countries use a two-dose vaccination schedule, with the first vaccine usually given at 12 months of age and the second at four years of age.
The vaccine provides very high and long-term protection and is indeed a typical example of the term “vaccine-preventable disease”. The two-dose regimen provides about 99% protection against measles infection.
In developing countries where vaccine uptake is low, one in ten people with measles dies. In developed countries, deaths occur mostly among unvaccinated people, at a rate of 1 in 1000–5000 cases of measles.
Measles is incredibly contagious. The basic reproduction number (R0) – the average number of people an infected person will infect in a susceptible population – has been estimated between 12 and 18.
The proportion of a population that must be vaccinated to control an outbreak and reduce community transmission is known as the herd immunity threshold (HIT).
For measles, 95% vaccination coverage is generally considered the magic number for contracting measles.
Most countries in the world are slightly below this limit, with global coverage of about 71% for two doses and 81% for single dose coverage.
Globally, significant progress has been made in reducing all-cause mortality in children under five years of age. Annual deaths have dropped from 12.5 million in 1990 to 5.2 million in 2019. However, declining vaccination coverage could reverse these gains.
Even if children survive measles, there is a possibility of long-term damage to their immune systems, which has been described as a “form of immunological amnesia.” In the unvaccinated population in severe cases of measles, a loss of 40% of the antibodies that normally recognize the pathogen was observed.
After a mild case of measles, unvaccinated children lost 33% of these antibodies. In comparison, measurements in healthy control groups showed a loss of 10% of antibodies over similar or longer periods of time.
The anti-vaccine advocacy has led to false rumors and scary stories, such as former physician and anti-vaccine activist Andrew Wakefield’s false claims that the MMR vaccine causes autism.
This belief has been preserved. For example, a 2020 US population survey found: “18% of our respondents incorrectly stated that it was accurate enough to say that vaccines cause autism.”
Disinformation has been rampant since the beginning of the Covid pandemic. There is a risk that this misinformation will lead to higher levels of vaccine hesitancy and the abandonment of routine immunizations.
Measles spreads easily and is a severe infection in the short and long term among unvaccinated populations. Immunization campaigns are urgently needed to increase protection against vaccine-preventable diseases around the world.
The report was prepared by Michael Head, Senior Research Fellow in Global Health at the University of Southampton.
Source: Science Alert