Written by Baxi Webster, CNN Mexico City, Mexico, and Ann-Eve Corrales, CNN
The health ministry in Quebec recently reported more than 1,000 new cases of rubella, or “Polio-like” rash caused by the vaccine for measles, mumps and rubella. The outbreak started a year ago when 500 new cases were recorded.
Here’s what you need to know:
So how did this happen?
The region has three groups of people most at risk of rubella — children, pregnant women and older adults. Rubella is most commonly spread through the air through coughing or sneezing.
The four-dose rubella vaccination series includes six injections that are administered around the time children are 2, 4, 6 and 12 years old.
Because of the high protection given by vaccination, the majority of people who received a second round of vaccination between ages 6 and 9 probably didn’t get the third dose, according to a study published in the journal Vaccine in 2017.
That’s because the previous two doses are usually given before the age of 10. In the past, infants weren’t offered a third dose until they were 9 months old and possibly later.
In addition, the National Registry of Central Canada (FRNC) didn’t record every required vaccination. And most people in that age group no longer need the third round of vaccination, the Health Ministry says.
What is rubella?
Rubella is a viral disease caused by the rubella virus that infects the surface of the outer membrane of the brain and the outermost part of the cheek. After passing through the nose, mouth and eyes, rubella gets into the bloodstream and then the veins and heart. The effect is a one- or two-day rash, often red and swollen.
The viral infection is not serious but can cause complications including hearing loss, vision loss, nerve damage and death in newborn babies.
Why are the doses becoming less effective?
Recent research suggests that the anti-rubella vaccine wears off more quickly and the dose itself is less powerful.
Between 2000 and 2017, the overall incidence of varicella, or chickenpox, increased by 68%, which likely contributed to increased rates of rubella. Furthermore, levels of certain immune responses, such as one that protects against leukemia, are decreasing with age.
In an effort to combat the spread of rubella, which is a congenital infection, the average age of first immunization is now 8.3 years, compared with 7.7 years a decade ago.
How many new cases have been reported this year?
As of June 14, 1,023 cases have been reported in Quebec. Over 200 of these new cases (39%) were contracted via the female spouse of a recipient of the rubella vaccine.
The majority of the cases (60%) are concentrated in the Saint-Jérôme-de-Vaudreuil-Rivière-du-Loup area, where 49 cases have been reported. The rest of the province’s districts have also seen more cases, ranging from 2 to 19. In the rest of Canada, fewer than 100 cases have been reported.
What’s the alternative?
André Girard, the former provincial health minister, believes that vaccination may have to be given in more doses in the future to prevent rubella, according to The Canadian Press.
“A vaccination of six vaccinations of four doses each, rather than of three vaccinations of three doses each, would be a more effective intervention against rubella,” Girard told reporters in April.
In the meantime, Quebec has scheduled a course of immunization for every child born after Nov. 1, at the cost of C$86.72 ($66.77) per dose, from July 25 to Sept. 2, 2019.