This year, the National Institute for Communicable Diseases (NICD) has issued reports on three outbreaks of vaccine-preventable diseases — measles, mumps and diphtheria. 

The current measles outbreak started late in 2022. On 19 June 2023, the total number of measles cases detected was 1,067 across the eight provinces.

Measles is a highly contagious disease caused by a virus. The most common symptoms are fever and a rash that looks like small, flat, red spots all over the body, which do not form blisters. Other symptoms include a cough, conjunctivitis and a runny nose. The virus can cause severe complications like encephalitis (an infection in the brain) as well as blindness, diarrhoea and dehydration. It can be deadly, and infants under two years of age are most at risk.

On 19 May, the NICD issued an alert for healthcare workers that two cases of diphtheria, a contagious and potentially life-threatening bacterial infection, had been detected in April.

Read more in Daily Maverick: Health Minister Phaahla calls for vigilance after two cases of contagious diphtheria confirmed in SA

On 26 May, a mumps outbreak was confirmed and the NICD has identified 580 positive cases this year. But based on data from the National Health Laboratory Service, the mumps outbreak had very much dissipated as of the end of April, said Professor Shabir Madhi, the dean of health sciences and professor of vaccinology at the University of the Witwatersrand.

Understanding mumps

Mumps is an acute viral infection caused by the rubulavirus, also known as the mumps virus, that predominantly affects children.

Although mumps can be avoided through vaccination, the mumps vaccine is not part of the Expanded Programme of Immunisation (EPI) in the public health sector, and occasional mumps outbreaks are to be expected, said Dr Lesley Bamford, a child health specialist at the National Department of Health.

“Although mumps is vaccine-preventable, we do not currently consider it to be a priority condition to target through vaccination,” she said. The MMR vaccine (measles, mumps and rubella) is available in the private sector for roughly R160.

While it generally causes only mild and self-limiting illness, especially during early childhood, mumps can cause more serious problems such as inflammation of the testes in adolescents and adults.

Read more in Daily Maverick: Are measles, mumps and diphtheria outbreaks harbingers of worse to come? 

Is confidence in childhood vaccines wavering?

The Department of Health does not have any reliable or representative data about confidence in childhood vaccines in South Africa, although historically it has been high, said Bamford. There are concerns that there might be knock-on effects related to the vaccine hesitancy experienced during Covid vaccination.

“We’ve received some anecdotal reports of that. But our coverage of childhood vaccines has recovered to pre-Covid levels. So, we’re not actually seeing any definite evidence of increased vaccine hesitancy around childhood vaccines.

“But obviously, it’s something that we are very concerned about and are monitoring carefully, and trying to ensure that vaccine confidence remains high and that we make childhood vaccines as available and accessible as possible,” Bamford said. “Because that’s really what we understand to drive uptake of vaccines — they have to be readily available, easily available, and people have to have confidence and value vaccination.

“Probably the main reason driving vaccine confidence in childhood vaccines is that they have been around for a long time and it’s not something new. People regard vaccination as part of childhood,” she said.

Education also plays an important role in vaccine confidence.

“With Covid vaccine hesitancy, we saw a lot of misinformation and sometimes unwillingness by people to accept evidence-based information from experts,” she said.

“We put a lot of effort into providing accurate information to parents and caregivers in the hope and expectation that will increase confidence in vaccines.”

There is heterogeneity in vaccine coverage in South Africa, Madhi said.

“The target is that all districts should have more than 90% of children fully vaccinated. In South Africa, this ranges from the mid-60s to above 90% at the subdistrict level. Unfortunately, the suboptimal vaccine coverage, which is indicative of dysfunctional primary healthcare services, lends itself to South Africa being prone to outbreaks of vaccine-preventable diseases and unnecessary loss of lives,” he said.

While the Department of Health does not suggest there’s been a decline in childhood vaccination compared with pre-Covid levels, coverage is still low in many subdistricts, Madhi said.

A resurgence in vaccine-preventable diseases

There is a potential for a resurgence of vaccine-preventable diseases and that is something the Department of Health monitors very carefully, Bamford said.

“Each disease is a little bit different. So, one of the challenges with measles is that because it’s so infectious, you need to achieve a very high coverage, 95% coverage, to ensure that you don’t experience any outbreaks. Whilst the majority of children in South Africa are vaccinated, we don’t achieve that 95% coverage so we do remain at risk of having measles outbreaks every five to eight years,” she said.

Read more in Daily Maverick: Poor vaccine coverage adding to heightened SA measles outbreak risk, experts say

Madhi concurs that there is potential for a resurgence of vaccine-preventable diseases, such as the whooping cough outbreak that affected adults and was more severe than the outbreaks experienced before Covid.

“We do vaccinate against pertussis [whooping cough]. However, vaccine coverage is not what it should be, which is more than 90% and the protection of the pertussis vaccine used in South Africa wanes after five to seven years,” he said. 

“In the absence of a booster dose every 10 years, we have a build-up of susceptibility, which contributes to the outbreak. This was likely compounded during the Covid pandemic period when there was a disruption of circulation of pertussis, which likely also led to a further build-up of susceptibility (as people will not have developed immunity from natural exposure as well). This immunity gap likely contributed to the pertussis outbreak in April 2023, and possibly also the measles outbreak we had earlier in the year,” he said. 

A possible resurgence of polio is also a concern.

“South Africa is currently polio-free, but there is a risk of importation of cases from surrounding countries. We have also seen two cases of diphtheria. So really, as long as our populations are not fully vaccinated against all the vaccine-preventable diseases that we target, there is always a risk of the country experiencing outbreaks,” Bamford said. 

Regarding the measles outbreak, there were more than 1,000 cases, with many of them being in slightly older children in whom measles is a relatively mild disease and therefore did not place a strain on the health system.

“However, we needed to implement a measles vaccination campaign where we vaccinated 10 million children and that takes a lot of resources, and a lot of the time of healthcare workers, who otherwise would be providing other services,” she said.

There are significant costs in responding to outbreaks.

“It really is in everyone’s interest to prevent such outbreaks. The simple message is really just a request to caregivers and guardians to make sure that the children do benefit from all the vaccines that are available to them,” Bamford said. DM