Rubella spreads through respiratory droplets when an infected person coughs, sneezes, or talks. The virus travels in secretions from the nose and throat, and you can catch it through direct contact with an infected person or by breathing in droplets they’ve released into the air. It can also pass from a pregnant person to their developing baby through the placenta.
How the Virus Travels Between People
Rubella is caused by a virus that lives in the nose and throat. When someone with rubella breathes, talks, coughs, or sneezes, they release tiny droplets containing the virus into the air around them. You can become infected by inhaling these droplets or by touching a surface contaminated with them and then touching your mouth, nose, or eyes.
You can also catch rubella through direct close contact with an infected person, such as sharing utensils or kissing. The virus doesn’t spread as explosively as measles. In studies across 98 different settings worldwide, the basic reproduction number (a measure of how many people one sick person typically infects in a population with no immunity) was below 5 in the vast majority of cases. For comparison, measles has a reproduction number between 12 and 18. Rubella is contagious, but it requires closer or more prolonged contact to spread efficiently.
The Contagious Window
One of the trickiest things about rubella is that people can spread it before they know they’re sick. An infected person is contagious for roughly seven days before their rash appears and continues to shed the virus for about seven days after the rash starts. That means the highest risk of unknowingly passing it to others comes in the days before any visible symptoms show up.
The incubation period, the gap between catching the virus and developing symptoms, typically ranges from 14 to 21 days, with an average of about 17 days. During the later portion of that window, an infected person is already contagious even though they feel fine.
Spread Without Symptoms
Rubella is especially tricky because a significant number of infections produce no symptoms at all. Up to half of all rubella cases are subclinical, meaning the person never develops a rash or feels noticeably ill. These asymptomatic carriers can still shed the virus from their nose and throat and pass it to others without ever realizing they were infected. This silent transmission is one reason rubella can circulate in a community before anyone recognizes an outbreak.
Transmission During Pregnancy
Rubella can cross the placenta from a pregnant person to their developing baby. This is the most dangerous form of transmission because the virus can interfere with fetal development and cause congenital rubella syndrome (CRS). Babies born with CRS can have heart defects, hearing loss, vision problems, and intellectual disabilities.
The timing of infection during pregnancy matters enormously. Infection during the first 12 weeks poses the greatest risk, when the baby’s organs are forming most rapidly. Infection later in pregnancy carries a lower, though still real, chance of harm. This is the core reason rubella vaccination programs exist: not primarily to protect the person getting the shot, since rubella is usually mild in children and adults, but to prevent the virus from reaching pregnant people and their unborn babies.
Who Is Still at Risk
Rubella has been eliminated in many parts of the world thanks to widespread vaccination. The WHO verified rubella elimination in the Americas in 2015, and in 2025 announced that Japan and 21 Pacific island countries and areas have also achieved elimination. However, rubella still circulates in parts of Africa, Southeast Asia, and the Eastern Mediterranean where vaccine coverage remains lower.
In countries where rubella is eliminated, cases still occasionally appear when travelers bring the virus back from regions where it circulates. People most vulnerable to these imported cases include anyone who was never vaccinated, anyone who missed their second dose of the MMR vaccine, and pregnant individuals without immunity. A single dose of MMR vaccine is about 97% effective at preventing rubella, and two doses provide even stronger, longer-lasting protection.
How to Reduce the Risk of Spread
Vaccination is the most effective way to stop rubella from spreading. The MMR vaccine (measles, mumps, and rubella) is given in two doses during childhood, typically at 12 to 15 months and again at 4 to 6 years. Adults who are unsure of their vaccination history can get a blood test to check for immunity or simply receive a dose of MMR.
If someone is diagnosed with rubella, they should stay home and avoid contact with others, particularly pregnant people, for at least seven days after the rash appears. Standard respiratory hygiene helps too: covering coughs and sneezes, washing hands frequently, and avoiding sharing cups or utensils. But because people spread the virus before they know they have it, vaccination remains far more effective than isolation at preventing outbreaks.