Can vaccines stop the spread of the virus?

Vaccine Q & A

Health Canada has approved both the Pfizer-BioNTech and Moderna vaccines for use and other vaccines will shortly become available. Slowly, province-by-province, people are beginning to be vaccinated. There are, however, unanswered questions about these vaccines and here, we hope to provide you with some preliminary answers to some of the concerns being expressed from coast to coast to coast. 

Q: Can I still get the virus or spread it after I get the vaccine?

A: Unfortunately, there is no clear yes or no answer to this question. Thus far, not one of the vaccines tested has proven 100 percent effective so, possibly, yes, someone who has been vaccinated may still catch it. One thing that is important to remember though, is that you cannot get the virus from the vaccination. The Pfizer and Moderna trials primarily focused on whether people were protected from developing symptoms. It is still not clear whether or not those people who received vaccinations could develop asymptomatic infections and so, are capable of spreading it to others.

During the trials for both the Pfizer and Moderna vaccines, it seems that some people actually did catch the virus after their vaccinations, but they did not become as ill as those who only received a placebo. In the Pfizer study, for example, only one subject suffered a severe episode after contracting the virus, while nine in their placebo group experienced severity. In the Moderna study, not one single subject became severely ill after contracting the virus although some 30 people in the placebo group did suffer severe episodes.

All that to say, that it seems that these vaccines may be far more effective as agents that drastically reduce the severity of the virus than barriers to reducing transmission. The hope is that overall, one vaccine will emerge as the most effective at reducing transmission, but for now, the impact of the existing ones in making occurrences less severe, and curbing mortality, is very significant.

Q: Even after the vaccine, will I still need to still wear a mask?

A: Yes, you will still need to wear a mask. It takes time to develop vaccine-induced antibodies and both the Pfizer and Moderna vaccines require a booster dose approximately 25 days after the first shot. It takes about a month to achieve full protection after the vaccination. Also, it will take time to vaccinate all Canadians so until that happens, we won’t be able to tell how well the vaccine prevents infection or whether the virus can still be passed on.

While the vaccines protect people from becoming ill and being hospitalized, it’s still possible to carry the virus and be contagious to others. That’s why all vaccine recipients should still be wearing masks, practicing physical distancing and washing their hands.

Q: Are the vaccines safe?

A: Yes, they are considered to be safe. Some people have experienced mild side effects, reporting fever, headache, arm soreness, redness at the injection site and a feeling of fatigue. Side effects such as these are commonly experienced with many vaccines.

In the U.K., two health care workers experienced allergic reactions after receiving the Pfizer’s vaccine resulting in a recommendation from British health officials to those who have a history of “significant” allergic reactions not to take the vaccine.

Eight in 10 Canadians, however, report that they would get the vaccine when offered the opportunity. Just over half (53 per cent) of Canadians say they feel that it is totally safe to get inoculated.

Q: When will my kids get vaccinated?

A: A vaccine is not yet ready for kids. Neither vaccine has yet been tested in kids under 12. Vaccine researchers reportedly were waiting to discover the effectiveness of the vaccines first, but now that they appear effective at preventing symptoms, the benefit of giving the vaccine to children may outweigh any risks.

Pfizer has tested its vaccine in adolescents older than 12, while Moderna plans to test children around this age soon. A typical process of vaccine testing starts with adults, progresses to adolescents, and then on to younger children.

Q: Can these vaccines help us achieve herd immunity?

A: “Nobody actually knows the level of vaccine coverage to achieve community immunity or herd immunity. We have an assumption that you will probably need 60 to 70 per cent of people to be vaccinated. But we don’t know that for sure … that’s modelling. Lots of these calculations are being done but the bottom line is that we actually don’t know,” says Canada’s top doctor, Dr. Tam.

To put it bluntly, Tam is saying that roughly 28 million Canadians must receive the vaccine before we even have a prospect of community immunity.

Even then, reaching herd immunity around the world will require the equitable distribution of vaccines, which will be challenging given the situation of many third world countries. 

Q: I had it early on in the pandemic. Should I get vaccinated?

A: The answer is yes. Whether or not you’ve had a previous infection, the U.S. Centers for Disease Control and Prevention recommends that people should plan on getting vaccinated eventually.

After someone recovers from a bout with this virus, infectious disease experts say that your immune system should be able to identify it and protect against getting sick again right away. While scientists do not know how long immunity lasts, some recent research suggests that immunity could last for up to six months.

Q: Will the vaccines work on new strains of the virus?

A: The short answer is yes. The discovery of a new, potentially faster spreading strain of the virus in the U.K. has raised concerns, however, all viruses naturally evolve so this was not unexpected. Experts remain firm in their belief that the Pfizer and Moderna vaccines will be effective against small changes in the virus for several years.