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I work at a COVID-19 vaccine clinic. Here’s what people ask me when they’re getting their shot — and what I tell them

A medical student answers questions he gets asked at a COVID-19 vaccine clinic: Efficacy versus real-world effectiveness, immune response and how the mRNA vaccines compare to vaccines already in wide use.

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People getting vaccinated may still have questions about COVID-19 vaccines, like why it takes two doses — and then two weeks — to take full effect. THE CANADIAN PRESS/Ryan Remiorz

As a medical student working with Alberta Health Services to vaccinate people against COVID-19, I have been asked my fair share of questions about the COVID-19 vaccines — from the need for booster doses to rare side effects.

Click here for more articles in our series about vaccine confidence.

A few days ago, I told an individual who was about to receive her second dose of the Moderna vaccine, “We are expecting about 95 per cent immunity two weeks from today.” She paused and asked, “What does that even mean?”

That scenario has repeated itself a few more times since then. I usually respond with, “It means you have 95 per cent less chance of developing COVID-19 two weeks after you have been vaccinated with the second dose of an mRNA vaccine.”

But what’s the long story behind that?

mRNA vaccines

There are multiple vaccines against COVID-19. I’ll focus on the Moderna and Pfizer-BioNTech mRNA vaccines used in Canada. They both received emergency use authorization from the U.S. Food and Drug Administration (FDA) and Health Canada in December 2020. The Pfizer-BioNTech vaccine also received full FDA approval in August 2021. Now that it is fully approved, the Pfizer-BioNTech vaccine is also known by a brand name — Comirnaty — but it’s the exact same vaccine that’s been in use since December 2020.

Both the Moderna and Pfizer-BioNTech vaccines require two doses given at least three to four weeks apart. The mRNA (or messenger RNA) in the vaccines contains the instructions for how to make the now-well-known spike protein on the surface of SARS-CoV-2, the virus that causes COVID-19.

An arm getting an injection
Once the mRNA vaccine is injected, it carries instructions to cells for how to make the SARS-CoV-2 virus’s spike protein, so the immune system can learn to recognize it and build an immune response to it. (AP Photo/Rogelio V. Solis)

Once it is injected into a muscle in the upper arm, this mRNA gives the muscle’s cells the instructions to make the spike protein. The immune system practises combating this protein and learns how to react when it recognizes something that has that spike protein on it.

Down the line, if we are exposed to the actual SARS-CoV-2 virus, our body knows how to defend against the virus because it has built immunity by making antibodies against the spike protein on the surface of the virus. These antibodies are our bodies’ protective proteins against SARS-CoV-2.

Efficacy vs. effectiveness

The Pfizer-BioNTech and the Moderna vaccines are extremely efficacious and effective against COVID-19. But what do efficacious and effective mean in the context of a vaccine?

Vaccine efficacy is defined as the reduction in the rate of developing disease in vaccinated people compared to unvaccinated people. First, we would calculate the difference in cases between the two groups and then divide it by the rate of unvaccinated cases. For example, if eight out of 21,830 vaccinated people and 162 out of 21,830 unvaccinated people develop the disease, the efficacy of that vaccine would be calculated as:

(162 / 21830 - 8 / 21830) / (162 / 21830) = 95 per cent

These numbers are the actual numbers out of the Pfizer-BioNTech trial, which reported 95 per cent efficacy in its clinical trials. Moderna reported a similar number (94.5 per cent efficacy) in its trials.

Vaccine efficacy is usually measured under specific controlled environments and in the setting of double-blind randomized controlled trials (RCTs). A double-blind RCT is a study in which the participants are randomly assigned to either a placebo (no vaccine) or intervention (vaccine) group and neither the researchers nor the participants are aware which group they are assigned to. This setting reduces bias and increases the accuracy of the studies.

Now that we know how efficacy is measured, let’s see what 95 per cent efficacy really means. In simple terms, 95 per cent efficacy means that vaccinated people have a 95 per cent lower chance of developing COVID-19. So, if out of 10,000 unvaccinated people, 100 people get the disease, out of 10,000 vaccinated people, only five people might get the disease.

Real-world effectiveness

People getting vaccinated at an arena set up as a mass vaccination clinic
People receive a dose of the COVID-19 vaccine at a mass vaccination clinic at Scotiabank Arena in Toronto on June 27, 2021. For those getting a second dose, the vaccine would take full effect two weeks later. THE CANADIAN PRESS/Cole Burston

Vaccine effectiveness, however, is different from efficacy. Effectiveness is how well a vaccine works in reducing the rate of disease in vaccinated people compared to unvaccinated people under real-world conditions.

It’s worth noting that most studies have defined developing disease as testing positive for COVID-19 and having at least one symptom. The efficacy numbers can change based on the circumstances under which the vaccines are tested. For example, the location of testing, the method of testing, the presence of specific strains or variants of a disease-causing virus and the diversity of the participants can affect the efficacy numbers. That’s why demographic information is collected in clinical trials, including Moderna’s and Pfizer-BioNTech’s vaccine trials.

This means we can’t directly compare the efficacy of one vaccine to another if they have not been tested under the exact same conditions.

How well are the mRNA vaccines working?

Empty vials of Moderna's COVID-19 vaccine
Preliminary studies suggest mRNA vaccines are about 90 per cent effective under real-world circumstances. THE CANADIAN PRESS/Lars Hagberg

With more than five billion doses administered around the world, we are at a point where we can also look at the effectiveness of the COVID-19 vaccines. Preliminary studies have shown that both mRNA vaccines are about 90 per cent effective in the real world against COVID-19. The Alberta government has reported 93 per cent effectiveness from the Moderna and 90 per cent effectiveness from the Pfizer-BioNTech vaccine.

And why does it take two weeks to develop that level of immunity? The process of a vaccine making our bodies immune against a disease has multiple steps. Remember the protective proteins called antibodies? One of the last steps in the immunity process is making those antibodies.

Based on the studies done by the vaccine makers, at around 14 days after the second dose, our bodies have made enough antibodies to recognize and fight SARS-CoV-2, hence the two-week rule before you are considered fully vaccinated.

One important statistic that needs to be mentioned is that both mRNA vaccines have been shown to prevent hospitalizations and deaths. This means that even in the rare case of a vaccinated individual developing COVID-19, the likelihood of them being hospitalized or dying is very much lower than if they hadn’t been vaccinated.

How do COVID-19 vaccines compare to others?

Another question I’ve been asked is how the effectiveness from the COVID-19 vaccines compares to the vaccines made for other diseases. Well, the MMR vaccine is 97 per cent effective against measles and rubella and 88 per cent against mumps. The effectiveness of the DTaP vaccine (diphtheria, tetanus, acellular pertussis) is between 80-85 per cent. The effectiveness of the flu vaccine hovers between 10-60 per cent depending on the year, the strains the vaccine protects against each year and the actual strains causing influenza and influenza-like diseases.

These numbers all reflect the reduction in the rate of disease between vaccinated and unvaccinated people. So next time you hear a vaccine is 95 per cent effective, that doesn’t mean five per cent of the people who got the vaccine will develop the disease; it means that vaccinated people have 95 per cent less chance of developing the disease compared to unvaccinated people.

Do you have a question about COVID-19 vaccines? Email us at ca‑vaccination@theconversation.com and vaccine experts will answer questions in upcoming articles.

Ehsan Misaghi does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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There will soon be one million seats on this popular Amtrak route

“More people are taking the train than ever before,” says Amtrak’s Executive Vice President.

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While the size of the United States makes it hard for it to compete with the inter-city train access available in places like Japan and many European countries, Amtrak trains are a very popular transportation option in certain pockets of the country — so much so that the country’s national railway company is expanding its Northeast Corridor by more than one million seats.

Related: This is what it's like to take a 19-hour train from New York to Chicago

Running from Boston all the way south to Washington, D.C., the route is one of the most popular as it passes through the most densely populated part of the country and serves as a commuter train for those who need to go between East Coast cities such as New York and Philadelphia for business.

Veronika Bondarenko captured this photo of New York’s Moynihan Train Hall. 

Veronika Bondarenko

Amtrak launches new routes, promises travelers ‘additional travel options’

Earlier this month, Amtrak announced that it was adding four additional Northeastern routes to its schedule — two more routes between New York’s Penn Station and Union Station in Washington, D.C. on the weekend, a new early-morning weekday route between New York and Philadelphia’s William H. Gray III 30th Street Station and a weekend route between Philadelphia and Boston’s South Station.

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According to Amtrak, these additions will increase Northeast Corridor’s service by 20% on the weekdays and 10% on the weekends for a total of one million additional seats when counted by how many will ride the corridor over the year.

“More people are taking the train than ever before and we’re proud to offer our customers additional travel options when they ride with us on the Northeast Regional,” Amtrak Executive Vice President and Chief Commercial Officer Eliot Hamlisch said in a statement on the new routes. “The Northeast Regional gets you where you want to go comfortably, conveniently and sustainably as you breeze past traffic on I-95 for a more enjoyable travel experience.”

Here are some of the other Amtrak changes you can expect to see

Amtrak also said that, in the 2023 financial year, the Northeast Corridor had nearly 9.2 million riders — 8% more than it had pre-pandemic and a 29% increase from 2022. The higher demand, particularly during both off-peak hours and the time when many business travelers use to get to work, is pushing Amtrak to invest into this corridor in particular.

To reach more customers, Amtrak has also made several changes to both its routes and pricing system. In the fall of 2023, it introduced a type of new “Night Owl Fare” — if traveling during very late or very early hours, one can go between cities like New York and Philadelphia or Philadelphia and Washington. D.C. for $5 to $15.

As travel on the same routes during peak hours can reach as much as $300, this was a deliberate move to reach those who have the flexibility of time and might have otherwise preferred more affordable methods of transportation such as the bus. After seeing strong uptake, Amtrak added this type of fare to more Boston routes.

The largest distances, such as the ones between Boston and New York or New York and Washington, are available at the lowest rate for $20.

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The next pandemic? It’s already here for Earth’s wildlife

Bird flu is decimating species already threatened by climate change and habitat loss.

I am a conservation biologist who studies emerging infectious diseases. When people ask me what I think the next pandemic will be I often say that we are in the midst of one – it’s just afflicting a great many species more than ours.

I am referring to the highly pathogenic strain of avian influenza H5N1 (HPAI H5N1), otherwise known as bird flu, which has killed millions of birds and unknown numbers of mammals, particularly during the past three years.

This is the strain that emerged in domestic geese in China in 1997 and quickly jumped to humans in south-east Asia with a mortality rate of around 40-50%. My research group encountered the virus when it killed a mammal, an endangered Owston’s palm civet, in a captive breeding programme in Cuc Phuong National Park Vietnam in 2005.

How these animals caught bird flu was never confirmed. Their diet is mainly earthworms, so they had not been infected by eating diseased poultry like many captive tigers in the region.

This discovery prompted us to collate all confirmed reports of fatal infection with bird flu to assess just how broad a threat to wildlife this virus might pose.

This is how a newly discovered virus in Chinese poultry came to threaten so much of the world’s biodiversity.

H5N1 originated on a Chinese poultry farm in 1997. ChameleonsEye/Shutterstock

The first signs

Until December 2005, most confirmed infections had been found in a few zoos and rescue centres in Thailand and Cambodia. Our analysis in 2006 showed that nearly half (48%) of all the different groups of birds (known to taxonomists as “orders”) contained a species in which a fatal infection of bird flu had been reported. These 13 orders comprised 84% of all bird species.

We reasoned 20 years ago that the strains of H5N1 circulating were probably highly pathogenic to all bird orders. We also showed that the list of confirmed infected species included those that were globally threatened and that important habitats, such as Vietnam’s Mekong delta, lay close to reported poultry outbreaks.

Mammals known to be susceptible to bird flu during the early 2000s included primates, rodents, pigs and rabbits. Large carnivores such as Bengal tigers and clouded leopards were reported to have been killed, as well as domestic cats.

Our 2006 paper showed the ease with which this virus crossed species barriers and suggested it might one day produce a pandemic-scale threat to global biodiversity.

Unfortunately, our warnings were correct.

A roving sickness

Two decades on, bird flu is killing species from the high Arctic to mainland Antarctica.

In the past couple of years, bird flu has spread rapidly across Europe and infiltrated North and South America, killing millions of poultry and a variety of bird and mammal species. A recent paper found that 26 countries have reported at least 48 mammal species that have died from the virus since 2020, when the latest increase in reported infections started.

Not even the ocean is safe. Since 2020, 13 species of aquatic mammal have succumbed, including American sea lions, porpoises and dolphins, often dying in their thousands in South America. A wide range of scavenging and predatory mammals that live on land are now also confirmed to be susceptible, including mountain lions, lynx, brown, black and polar bears.

The UK alone has lost over 75% of its great skuas and seen a 25% decline in northern gannets. Recent declines in sandwich terns (35%) and common terns (42%) were also largely driven by the virus.

Scientists haven’t managed to completely sequence the virus in all affected species. Research and continuous surveillance could tell us how adaptable it ultimately becomes, and whether it can jump to even more species. We know it can already infect humans – one or more genetic mutations may make it more infectious.

At the crossroads

Between January 1 2003 and December 21 2023, 882 cases of human infection with the H5N1 virus were reported from 23 countries, of which 461 (52%) were fatal.

Of these fatal cases, more than half were in Vietnam, China, Cambodia and Laos. Poultry-to-human infections were first recorded in Cambodia in December 2003. Intermittent cases were reported until 2014, followed by a gap until 2023, yielding 41 deaths from 64 cases. The subtype of H5N1 virus responsible has been detected in poultry in Cambodia since 2014. In the early 2000s, the H5N1 virus circulating had a high human mortality rate, so it is worrying that we are now starting to see people dying after contact with poultry again.

It’s not just H5 subtypes of bird flu that concern humans. The H10N1 virus was originally isolated from wild birds in South Korea, but has also been reported in samples from China and Mongolia.

Recent research found that these particular virus subtypes may be able to jump to humans after they were found to be pathogenic in laboratory mice and ferrets. The first person who was confirmed to be infected with H10N5 died in China on January 27 2024, but this patient was also suffering from seasonal flu (H3N2). They had been exposed to live poultry which also tested positive for H10N5.

Species already threatened with extinction are among those which have died due to bird flu in the past three years. The first deaths from the virus in mainland Antarctica have just been confirmed in skuas, highlighting a looming threat to penguin colonies whose eggs and chicks skuas prey on. Humboldt penguins have already been killed by the virus in Chile.

A colony of king penguins.
Remote penguin colonies are already threatened by climate change. AndreAnita/Shutterstock

How can we stem this tsunami of H5N1 and other avian influenzas? Completely overhaul poultry production on a global scale. Make farms self-sufficient in rearing eggs and chicks instead of exporting them internationally. The trend towards megafarms containing over a million birds must be stopped in its tracks.

To prevent the worst outcomes for this virus, we must revisit its primary source: the incubator of intensive poultry farms.

Diana Bell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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This is the biggest money mistake you’re making during travel

A retail expert talks of some common money mistakes travelers make on their trips.

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Travel is expensive. Despite the explosion of travel demand in the two years since the world opened up from the pandemic, survey after survey shows that financial reasons are the biggest factor keeping some from taking their desired trips.

Airfare, accommodation as well as food and entertainment during the trip have all outpaced inflation over the last four years.

Related: This is why we're still spending an insane amount of money on travel

But while there are multiple tricks and “travel hacks” for finding cheaper plane tickets and accommodation, the biggest financial mistake that leads to blown travel budgets is much smaller and more insidious.

A traveler watches a plane takeoff at an airport gate.

Jeshoots on Unsplash

This is what you should (and shouldn’t) spend your money on while abroad

“When it comes to traveling, it's hard to resist buying items so you can have a piece of that memory at home,” Kristen Gall, a retail expert who heads the financial planning section at points-back platform Rakuten, told Travel + Leisure in an interview. “However, it's important to remember that you don't need every souvenir that catches your eye.”

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According to Gall, souvenirs not only have a tendency to add up in price but also weight which can in turn require one to pay for extra weight or even another suitcase at the airport — over the last two months, airlines like Delta  (DAL) , American Airlines  (AAL)  and JetBlue Airways  (JBLU)  have all followed each other in increasing baggage prices to in some cases as much as $60 for a first bag and $100 for a second one.

While such extras may not seem like a lot compared to the thousands one might have spent on the hotel and ticket, they all have what is sometimes known as a “coffee” or “takeout effect” in which small expenses can lead one to overspend by a large amount.

‘Save up for one special thing rather than a bunch of trinkets…’

“When traveling abroad, I recommend only purchasing items that you can't get back at home, or that are small enough to not impact your luggage weight,” Gall said. “If you’re set on bringing home a souvenir, save up for one special thing, rather than wasting your money on a bunch of trinkets you may not think twice about once you return home.”

Along with the immediate costs, there is also the risk of purchasing things that go to waste when returning home from an international vacation. Alcohol is subject to airlines’ liquid rules while certain types of foods, particularly meat and other animal products, can be confiscated by customs. 

While one incident of losing an expensive bottle of liquor or cheese brought back from a country like France will often make travelers forever careful, those who travel internationally less frequently will often be unaware of specific rules and be forced to part with something they spent money on at the airport.

“It's important to keep in mind that you're going to have to travel back with everything you purchased,” Gall continued. “[…] Be careful when buying food or wine, as it may not make it through customs. Foods like chocolate are typically fine, but items like meat and produce are likely prohibited to come back into the country.

Related: Veteran fund manager picks favorite stocks for 2024

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