To explain the differences in getting COVID-19 with and without a vaccine, we’ve divided this explainer into two categories: 1) transmission (how likely you are to get the virus and spread the virus to someone else), and 2) disease outcomes (how severe one’s case of COVID-19 is likely to be if infected).

1) Transmission:

Vaccines are helpful at reducing transmission within a population both in terms of lowering the chance for vaccinated people to become infected in the first place, and in terms of lowering the chance for vaccinated people to spread the disease to others. 

Vaccines help reduce transmission in the first way (in terms of lowering the chance for vaccinated people to become infected in the first place) is because vaccines help people build up immunity to a virus so that when they are exposed to it, their bodies help protect them from becoming infected.

Vaccines help reduce transmission in the second way (in terms of lowering the chance for vaccinated people to spread the disease to others) because people who are vaccinated and get a breakthrough infection are less likely to infect others based on the fact that they shed the virus for a much shorter time during their infection when compared to unvaccinated individuals.

According to a study published in the New England Journal of Medicine, vaccinated individuals clear the virus from their system in about 5 days, compared to 7 days for people who are unvaccianted. 

Another study from the University of Oxford examined the contacts of confirmed COVID-19 cases who were vaccinated with the Pfizer-BioNTech or AstraZeneca vaccine. The study found that fewer close contacts of vaccinated people went on to become infected than close contacts of unvaccinated people, indicating that the vaccines reduced transmission. Transmission rates were lower for both vaccines. In addition, people who received two doses of either vaccine were found to transmit less to their contacts than individuals who had only received one dose. 

2) Disease outcomes: 

In terms of disease outcomes, people who are vaccinated have a much lower chance of having a severe case, including a much lower chance of hospitalization and death. A study carried out by the U.S.CDC showed that having immunity either through vaccination or previous infection profects against hospitalization from COVID-19 mainly caused by Alpha and Delta variants. 

Research suggests that while people who are vaccinated are more likely to get the Omicron variant than other variants, vaccination continues to provide a high level of protection against severe disease and hospitalisation linked to Omicron.

lower protection against getting COVID-19 with the Omicron variant from both vaccine and infection-induced immunity than Alpha and Delta variants, but still more protection than someone who has neither been vaccinated nor had a previous COVID-19 infection. Data from South Africa, for instance, shows that people who received two doses of a COVID-19 vaccine have up to 70% protection for hospitalisation. 

Additional protection from COVID-19 booster shots has also been shown. Similar data from the UK, for instance, shows that though protection goes down a few months after vaccination, protection against hospitalisation rises again to 90% after a booster shot. Researchers in 

It is true that both vaccinated and unvaccinated individuals can get COVID-19, especially with the rise of Omicron. However, the risk for vaccinated individuals is still much lower, and they are less likely to develop symptoms or severe health outcomes from the infection.

According to the U.S. Center for Disease Control and Prevention (U.S. CDC) monitoring data, unvaccinated people are four times more likely to test positive for Covid-19, and 15 times more likely to die from a Covid-19 infection. Recent monitoring data from December 2021 shows little over twice the number of unvaccinated cases compared to vaccinated cases. 

The gap is even bigger between the number of cases among fully vaccinated individuals who received a booster shot, and the unvaccinated (nearly four times as many unvaccinated cases). 

Hospitalizations among the unvaccinated are higher in all age groups, the lowest being ages 12-17 years, who are nine times more likely to be hospitalized due to Covid-19, and highest among adults 50 years and older. The overall rate of hospitalizations was nearly 4 cases of vaccinated people per 100,000 people compared to nearly 67 cases of hospitalizations among unvaccinated people per 100,000 population 

Experts suggest that the gap between the unvaccinated and vaccinated could be even larger than the numbers suggest, because people can still be hospitalized for other reasons (like heart disease) and test positive while being screened in the hospital, without Covid-19 being the main reason for their admittance. In New York state, for example, over 40% of hospital cases with Covid-19 were actually admitted for other reasons. 

Data from Europe shows that despite the Omicron variant spreading among vaccinated people, the overall severity of the surge is low. This is likely because of the protection that vaccination with two doses and booster dose presents against severe illness from Omicron infection. Omicron can still infect vaccinated individuals, however the numbers of hospitalizations are by far mostly among the unvaccinated because of the protection of the vaccines.