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. The federal government expects to be able to offer free vaccination to all Canadians. Health officials have procured the most doses per capita for Canadians than any other country, but are also committed to supplying vaccines to low- and middle-income countries who weren鈥檛 able to order doses.

The Canadian government assembled a team of experts and officials months ago to prepare for vaccine rollout, including logistics and prioritization. From an operations standpoint, a Canadian military general is heading the rollout. From a prioritization standpoint, the (NACI), a long-established body that includes public health, infectious disease, and immunization policy experts, created a vaccine prioritization framework, released in early November. The framework determined that people and staff at long-term care facilities should be immunized first, then other health care workers and vulnerable populations, and finally the general population. For more details, including whether you can choose which vaccine to get and who gets priority, please read our explainer, Your COVID-19 vaccine rollout questions, answered.

It鈥檚 possible that vaccination could be required in certain education, health care and travel circumstances, said Chagla, and there is precedent for it.

In parts of South America and Africa, travellers are required to present a 鈥測ellow fever vaccination certificate鈥� to prove they are immune from the virus and won鈥檛 set off an outbreak. In Canadian schools, some provinces require children and adolescents to be immunized from a variety of illnesses before they can attend school, unless they have a medical exemption.

鈥淚 think you鈥檙e going to see some fairly forward-facing industries like travel industries, health care, schools, where this is probably going to be part of the mandate,鈥� said Chagla, noting that mandatory vaccinations get 鈥渄icey鈥� when it comes to employment law.

While no one can be forced to get an eventual COVID-19 vaccine, ethicists have urged for more clarity around what the rollout of vaccines will mean, including for millions of people who may choose not to get one.

鈥淭hat is an ethical concern because what will likely happen to people within that group is more and more opportunities may slowly be shut off to them,鈥� Kerry Bowman, a bioethicist and assistant professor at the University of Toronto鈥檚 faculty of medicine, told CTV National News.

Common side-effects will have already been identified since most adverse events associated with vaccines occur within a day of receiving the shot, said Bogoch, the most common of which is a sore arm.

鈥淭here are certain rare vaccine side effects that can occur two to four weeks after vaccination. They鈥檙e not very common at all,鈥� he said, adding that early data suggests the Pfizer and Moderna vaccine candidates, which use a relatively new mRNA technology, have not resulted in any notable side effects other than people feeling 鈥渇atigued or a little unwell鈥� in the day following vaccination.

The AstraZeneca and Janssen (Johnson & Johnson) vaccines are , and the side effects seen during clinical trials were similar to other types of vaccines.

A number of European countries did pause their use of the AstraZeneca vaccine amid reports of blood clots. Health Canada said there was no indication that the vaccine was the cause and that none of the identified batches under investigation in Europe were shipped to Canada. AstraZeneca Canada said the company completed a new safety review of 10 million patients who received the vaccine and uncovered 鈥渘o evidence of an increased risk 鈥� in any defined age group, gender, batch or in any particular country.鈥�

Chagla said he trusts that Health Canada, which is constantly monitoring safety reports, would step in if there was any concern.

No. The vaccine is preventative, not therapeutic. Someone with COVID-19 should remain isolated until full recovery and later seek vaccination. 鈥淭he recommendation is typically about 90 days or longer after an onset of the coronavirus to get the vaccine to offer longer-term immunity,鈥� Shapiro told 麻豆影视 Channel. 鈥淚t would act as a typical vaccine does for future forward immunity.鈥�

No. The federal and provincial governments are not implementing widespread routine screening before vaccinating individuals. 鈥淭hat would not be cost-effective,鈥� Shapiro told 麻豆影视 Channel. Instead, health officials developed a prioritization framework to determine who gets vaccinated first. 鈥淵ou would be getting the vaccine regardless, as long as you鈥檙e [part of the group] that鈥檚 stratified.鈥�

Yes. While research shows that COVID-19 antibodies are often detectable several months after infection, there have been several reports of reinfection.

鈥淲e know that those credible cases of reinfection are pretty much the tip of the iceberg,鈥� Bogoch told CTV鈥檚 Your Morning. 鈥淚t鈥檚 probably happening a lot more frequently than we would think.鈥�

There has been no evidence of 鈥渟terilizing immunity,鈥� adds Shapiro, meaning we can鈥檛 say if anyone infected with COVID-19 will be 鈥渋mmune for life.鈥� Whether or not you have COVID-19 antibodies from past infection, the vaccine is still recommended, she told 麻豆影视 Channel.

It鈥檚 likely that the majority of people with allergies will be able to receive the Pfizer-BioNTech vaccine and others, but experts stress that Canadians should go over the list of ingredients with their physician. On Dec. 12, Health Canada issued a notice that people with severe allergies to the ingredients in the Pfizer product should avoid the shot altogether.

鈥淚f you鈥檙e allergic to any of those ingredients you shouldn鈥檛 be getting this vaccine and luckily we have other vaccines that are in the pipeline and are hopefully going to be available in Canada soon,鈥� Bogoch told CTV鈥檚 Your Morning.

Yes. Guillain Barre syndrome is an uncommon condition in which someone鈥檚 immune system attacks their nerves and can result in weakness, tingling and paralysis. 鈥淚t鈥檚 a rare event. Most of the time people don鈥檛 know why Guillain-Barre happens, but it鈥檚 not something that usually happens on a repetitive basis,鈥� said Banerji. "Someone who's had Guillain-Barre, if they have any underlying conditions, [those conditions] may make them at risk for severe COVID-19 infection. If someone's at risk of severe disease from the virus, they should get the vaccine."

The messenger RNA vaccine by Pfizer-BioNTech does not contain preservatives. Mercury-based preservatives like thimerosal, which researchers have shown is safe in low doses and , have not been used in the majority of vaccines since the late 90s.

The Pfizer and Moderna vaccines are both 鈥渕essenger RNA鈥� or mRNA vaccines, which is a new kind of vaccine technology that is like 鈥済iving an instruction booklet for your cells to make antigens,鈥� said Chakrabarti in a phone interview with CTVNews.ca last month. In the absence of the coronavirus, a person鈥檚 cells would still be programmed to develop the antibodies that fight the virus off.

The AstraZeneca and Janssen vaccines use a more well-established approach that utilizes a harmless virus like the ones that can cause a common cold as a delivery system. The vaccine alters the virus, called a modified adenovirus vector, to mimic COVID-19 and thereby produce an immune response in the human body without making you sick.

Probably not. While study participants represented a wide spectrum of ages and ethnicities, they were also all generally healthy people, said Chagla in a phone interview with CTVNews.ca in November. In the past, when vaccines for other illnesses rolled out, they may have had strong data from clinical trials too. 鈥淏ut they鈥檙e not necessarily as good as patients get more complex, as their medications get more complex and their immune system diseases are more complex,鈥� he said.

Nonetheless, a real-world study published in February that looked at the Pfizer vaccine鈥檚 efficacy in more than 500,000 recipients found it 62 per cent effective at preventing disease after one shot and 92 per cent after both shots were administered. This was better than what many were expecting. Data from other trials, however, have demonstrated 鈥渕iraculous鈥� protection of at least 90 per cent just from the first dose.

In clinical trials, Pfizer was 95 per cent effective one week after the second dose in a study of about 44,000 participants; Moderna was 94.1 per cent effective two weeks after the second dose in studies of 30,000 participants. AstraZeneca was about 62 per cent effective two weeks after the second dose, while Janssen鈥檚 was 66 per cent effective two weeks after its single-dose vaccination.

It鈥檚 too early to know. The Pfizer and Moderna vaccines require two doses, separated by two weeks, but the second is not considered a 鈥渂ooster鈥� shot, which are given to prevent immunity from waning.

鈥淲e don鈥檛 have a clue how long immunity will last,鈥� said Bogoch over the phone with CTVNews.ca in November. 鈥淲e鈥檒l have clues about this longer-term after people are vaccinated to see how long immunity will last.鈥�

Booster shots are typically given several years after the first, though children will often receive them earlier to provide a more 鈥渞obust immune response,鈥� said Chagla. 鈥淔or most adult vaccinations you have a series [of doses], and things like the pneumonia shot or tetanus shot you do at five, 10-year intervals after getting it just knowing that immunity wanes in some of the older populations,鈥� he said.

As with any vaccine that requires multiple doses, the first dose exposes the body to the COVID-19 virus to kickstart an immune response. The second dose 鈥済ets the engine running quicker,鈥� infectious disease specialist Anna Banerji told CTVNews.ca. 鈥淭he second time the body sees the virus it responds quicker because the antibodies are there and you can have a much more immediate response.鈥�

It is still possible to contract COVID-19 after the first or second dose, but data from leading vaccines trials suggest they are effective in preventing infection.

The vaccines all have different requirements for transportation and storage. Pfizer鈥檚 vaccine needs to be kept at -70 C during those stages to remain effective, but it is not administered into someone鈥檚 veins at that temperature, assured Bogoch.

鈥淕od, that would suck. You鈥檇 get frostbite. That would cause tremendous damage,鈥� he said. 鈥淭he Pfizer vaccine is stable for about five days in a conventional refrigerator. The Moderna vaccine needs to be stored at -20 C but it鈥檚 stable in a refrigerator for about 30 days.鈥�

The AstraZeneca and Janssen vaccines can be stored between 2 C and 8 C, which experts consider a major logistical advantage for areas of the country that don鈥檛 have access to .

There are a variety of methods by which people can be vaccinated. Where someone lives may determine which vaccine they receive by which method.

鈥淚t鈥檚 going to depend on what vaccine is locally available, what resources are in that region to actually administer them,鈥� said Chagla, noting the different storage temperatures required of the vaccines.

Each province and territory has its own rollout plan, though in general, vaccines are by appointment and based on prioritized groups. Some pharmacies are also helping with the vaccination process. Check your for more information.

If someone is vaccinated and they come into contact with the virus, one of two things is going to happen, said Bogoch: 鈥淵ou鈥檙e either going to get the infection, or you鈥檙e not.鈥�

Early data from COVID-19 vaccine trials suggests that the probability of getting the infection is significantly lower in vaccinated people than in unvaccinated people. Similarly, the early data suggests severe illness is also less common in people who are vaccinated.

鈥淚t鈥檚 extremely important to note that we don鈥檛 have the data available, and we're only going by the snippets of data that we do have available,鈥� he added.

The National Advisory Committee on Immunization strongly recommends that everyone continues to practise all public health measures regardless of vaccination, because there is currently not enough data regarding the effectiveness of COVID-19 vaccines in preventing asymptomatic infection and reducing transmission of SARS-CoV-2, or the duration of the vaccine protection. There is also emerging evidence on the decreased efficacy of the vaccines against variants of concern.

Yes. While a minority of people get sick and die from COVID-19, that small group of people can still overwhelm the hospital system, said Chakrabarti.

鈥淥nce that happens, there鈥檚 a ripple effect that has effects on everybody鈥檚 health,鈥� he said, noting cancer screening appointments are cancelled and elective operations are postponed. This past winter, some of the largest hospitals in Canada were nearing capacity, threatening widespread cancellations of non-emergency surgeries that would further extend a health care backlog.

While some have suggested protecting the elderly and letting the virus 鈥渞ip鈥� through society to allow for natural herd immunity, Chakrabarti says it鈥檚 very difficult to protect all vulnerable people and the consequences of such a strategy can鈥檛 be understated.

鈥淭he cost of doing that is that you would overrun hospitals and there would be all sorts of collateral damage,鈥� he said.

Likely yes. Since the Pfizer-BioNTech and Moderna vaccines are not 鈥渓ive-virus鈥� vaccines, there is no concern that a suppressed immune system will get COVID-19 from these shots, said Shapiro. 鈥淭he concern is that they may not mount as large an immune response, but there is no reason to think that they will not be able to be given the vaccine,鈥� she told 麻豆影视 Channel. 鈥淟ooking at previous histories of this population, we worry about [them] getting sicker with the disease so usually they're a population we like to immunize.鈥�

Maybe, but it鈥檚 unlikely that individual people will get each of the Pfizer, Moderna, AstraZeneca, and Johnson & Johnson vaccines, or some other combination of vaccines, during the first rollout, said Chakrabarti.

鈥淭his stuff will be honed in the coming years as we start to get to know more and more. There is a precedent for using vaccines of slightly different mechanisms to give you a synergistic type of effect,鈥� he said, noting that high-risk populations are inoculated with both pneumonia vaccines on the market for a more powerful affect.

There鈥檚 also added benefit to having multiple vaccines on the market, whether or not an individual person receives multiple shots. The differences in the storage requirements alone provide important benefits, particularly to the developing world, noted Chagla.

鈥淩ight now it鈥檚 just a race to get a vaccine on the market rather than necessarily saying 鈥榃hat鈥檚 the optimal strategy?鈥欌�� he said. 鈥淎s things go on, we鈥檙e probably going to get more and more data to say which one is better in kids, which one is better in the elderly, which one is better in certain settings, or with certain medications. That鈥檚 the benefit fo having multiple on the market.鈥�

While some experts expect a feeling of 鈥渘ormal鈥� to return at some point next year, a complete return to normal might not come until 2022.

鈥淭he rollout of the vaccine is a gargantuan task,鈥� said Chakrabarti. 鈥淚 do completely expect that things will be back to normal sometime in 2022. I think 2021 will be a gradual and stepwise improvement in our daily lives and the case count.鈥�

Chagla expects people will begin to 鈥渟tep off the brake鈥� once the most vulnerable populations are vaccinated in the early months of 2021. Summer could be close to normal, he added. 鈥淲e鈥檙e going to see 鈥榥ormal鈥� starting to show up more and more and more as some of those higher-risk settings get more and more vaccinated,鈥� he said.

Yes. Until more of the population has been vaccinated, it鈥檚 likely that mask mandates will remain in place across much of Canada. While the COVID-19 vaccines being distributed have proven to be very effective at preventing infection, it鈥檚 still possible that inoculated individuals could be asymptomatic and unknowingly spread the disease. 鈥淭here鈥檚 nothing there [in Pfizer鈥檚 data] that suggests that people are less transmissible,鈥� Chagla told CTVNews.ca in December. 鈥淎ll we know is individuals who got the vaccine had less symptomatic disease than people who didn鈥檛 get the vaccine.鈥�

The National Advisory Committee on Immunization strongly recommends that everyone continues to practise all public health measures since there is not enough data yet on how effective the vaccines are at preventing transmissions. There is also emerging evidence on the decreased efficacy of the vaccines against variants of concern.

The approach to distributing the two-dose vaccines (Pfizer, Moderna, AstraZeneca) varies, but a number of jurisdictions across Canada began delaying administering second doses. This came after the National Advisory Committee on Immunization (NACI) recommended that the interval between the first and second shot be extended by up to four months when vaccine supplies are limited. The new advice is based on early real world data which showed sustained high levels of protection. In Quebec, for example, officials decided from the beginning to use all available vaccine supplies to provide more people with their first dose. Ontario switched its strategy to follow NACI鈥檚 recommendation and after the province was criticized for its slow rollout.

The COVID-19 vaccines currently in rotation have not been tested in children and most teens. Last month, Pfizer-BioNTech released more data from its clinical trials in which there were no people younger than 16 among all 43,448 participants. "They can't really say this vaccine is recommended for an age group that hasn't been tested yet," Dr. Anna Banerji, an infectious diseases pediatrician and associate professor of pediatrics at the University of Toronto, told CTVNews.ca in a phone interview last month.

The timeline for children becoming vaccinated in Canada depends on the results of clinical trials, availability of the vaccine and each province鈥檚 rollout of the drug, but targeting the start of the 2021-22 school year seems appropriate, according to the experts. Testing for the 12 to 15 age group are well under way outside Canada, so we may see a phased rollout for children as the clinical trial results come in. In Canada, authorities have approved a clinical trial for the Janssen vaccine in children ages 12 to 17.

None of the COVID-19 vaccines currently being administered in Canada are "live virus" vaccines, meaning they can't cause infection even in people with compromised immune systems. Other vaccines that use live virus, such as the yellow fever shot or MMR shot, aren't given to people with compromised immune systems because they could get infected. "But if you have a normal immune system, your body can mount an immune response," said Dr. Chakrabarti.

There are several scenarios that put people at risk of severe disease from COVID-19, including having diabetes, high blood pressure, a transplant, and undergoing chemotherapy treatment. But elderly people are prioritized above all because data still suggests they are most at risk. "If you take the entire pile of risk factors, the one that stands out by far is age," said Dr. Chakrabarti. "A completely healthy 80-year-old is much more likely to get severe illness from COVID-19 than a 40-year-old who's on immunosuppressive medication."

The initial vaccines were made to target the original SARS-CoV-2 virus. The development of more variants depends on how well the virus is under control, said Dr. Hassan Masri, an ICU physician and Associate Professor of Medicine at the University of Saskatchewan. "If you look at the variants, they are variants of places where the virus was very much out of control," he told 麻豆影视 Channel in February. "The chances of another variant coming alive is less likely to do with the vaccine, but more related to whether we will have excellent control of our numbers."

Thousands of people in Canada have received both already, as have likely millions in the U.S., U.K. and other countries. There are plenty of vaccines that people get within the same month, said Victoria, B.C., palliative care and family physician Dr. Amy Tan. "They're different mechanisms, they're different immune responses. Everything looks to be fine," she told 麻豆影视 Channel in February.

The Serum Institute of India (SII) vaccine COVISHIELD is a version of the AstraZeneca one. The company partnered with SII, the world鈥檚 largest vaccine manufacturer, to supply its vaccine to India and other countries under an exclusive sub-license. It was sponsored for use in Canada by Verity Pharmaceuticals, the Canadian importer and distributor. While they were approved as two separate vaccines, Health Canada said it for both vaccines and found the manufacturing processes and controls and the quality characteristics of both to be comparable.

The 62 per cent efficacy is based on a four-week gap between the first and second dose, says Dr. Supriya Sharma, the chief medical adviser at Health Canada, adding that there is some data that suggests that rises to 85 per cent if the gap between doses is increased to 12 weeks. Sharma notes that the same vaccine can have multiple trials with different methods and varying results.

For now, it is recommended that the vaccine be used for those under 65, due to insufficient data on older recipients. There are also some concerns around its effectiveness against the B.1.351 variant that is predominant in South Africa. Federal bodies stress that all three vaccines can lower hospitalizations and deaths due to COVID-19 and getting the AstraZeneca shot early is better than waiting for Pfizer or Moderna, which could take longer to reach some groups.

For perspective, Sharkawy points to the efficacy of flu vaccines.

鈥淎 great match between a circulating flu strain and the vaccine in a given year might not exceed 60 per cent. If the flu vaccine is delivered widely in the community, we see dramatic reduction in every bad outcome,鈥� he told 麻豆影视 Channel in February.