‘I acquired AstraZeneca for my first dose. Which ought to I get for my second?’ A COVID vaccination information – Wholesome Debate

Obtain choice information right here

Why are we speaking about this?

For those who had AstraZeneca for dose 1, you now have a alternative. You may get AstraZeneca for dose 2 or you may get a dose of Moderna or Pfizer as an alternative. Moderna and Pfizer are mRNA vaccines and are very comparable. AstraZeneca is from one other group of vaccines known as viral vector vaccines.

For this information, we’re sharing knowledgeable recommendation from the Nationwide Advisory Committee on Immunization (NACI), the Public Well being Company of Canada and Well being Canada. You may really feel assured that you’ve got essentially the most up-to-date science-based data to make your choice.

  1. Safety after two doses

Crucial choice is to get a second dose. Dose 2 provides you with stronger and longer lasting safety. Two doses of AstraZeneca are very efficient at stopping critical sickness from the unique COVID-19 and early variants. Early research present that folks additionally generate an excellent immune response (measured by cells of their blood) when Moderna or Pfizer are used after AstraZeneca. We’ve used totally different vaccines for boosters prior to now for different viruses like hepatitis A, influenza and polio. It’s protected and isn’t linked with any long-term unwanted effects. This technique is efficient and suggests {that a} second dose of Moderna or Pfizer must be a minimum of as protecting as two doses of AstraZeneca.

  1. Safety in opposition to new variants

The Delta variant first found in India is spreading shortly in Canada. Two vaccine doses defend you in opposition to Delta significantly better than one dose. Two doses of Moderna or Pfizer seem to supply extra safety in opposition to symptomatic an infection from Delta than two doses of AstraZeneca. For those who had AstraZeneca for dose 1, we don’t know but if getting Moderna or Pfizer for dose 2 provides you with higher safety from Delta or future variants.

  1. Danger of blood clots

AstraZeneca has been linked with a really uncommon however critical blood clotting illness known as Vaccine Induced Thrombotic Thrombocytopenia, or VITT. VITT might be deadly. Based on experiences from a number of international locations together with Canada, there are about 17 instances of VITT for each million individuals given dose 1 of AstraZeneca. For dose 2, the danger of VITT is estimated to be 2 for each million vaccinated. These estimates might change as extra individuals all over the world have dose 2 and we be taught extra. The Moderna and Pfizer vaccines don’t trigger VITT.

  1. Uncomfortable side effects

It’s common to have unwanted effects like a sore arm, fatigue, headache, fever or sore muscle groups after AstraZeneca, Moderna or Pfizer. This can be a signal your immune system is working to construct safety.

We don’t know but if you’ll have fewer or extra unwanted effects in case you select Moderna, Pfizer or AstraZeneca for dose 2.

  1. Availability

Canada is receiving rather more Moderna and Pfizer vaccine than AstraZeneca. That is anticipated to proceed all summer time. A lot of the worldwide provide of AstraZeneca is getting used elsewhere on the planet. It might be simpler and quicker to get Moderna or Pfizer for dose 2.

Understanding the analysis on utilizing two COVID-19 vaccine sorts.

What is thought about having AstraZeneca for dose 1 and dose 2?

The UK (U.Okay.) has one of many largest vaccine packages on the planet. Actual-world knowledge from Public Well being England reveals that two doses of AstraZeneca are 66 per cent efficient in defending individuals from a gentle, average or extreme COVID-19 an infection. This implies they decrease an individual’s probabilities of getting COVID-19 by 66 per cent. Two doses of Moderna and Pfizer are 93 per cent efficient.

Researchers on the College of Edinburgh in Scotland additionally discovered that dose 1 of AstraZeneca or Pfizer is 90 per cent efficient at stopping individuals from getting sick sufficient that they should go to the hospital. One other examine from the U.Okay. of 150,000 individuals over age 70 discovered that 1 dose of AstraZeneca or Pfizer was 80per cent efficient at stopping individuals from needing hospital care.

Extra lately, the Delta variant has unfold quickly within the U.Okay. It’s spreading quickly in Canada, too. A brand new examine from the U.Okay. suggests one dose of AstraZeneca is 33 per cent efficient in opposition to symptomatic an infection from the Delta variant. Two doses are 60 per cent efficient. The identical examine confirmed one dose of Pfizer is 33 per cent efficient and two doses of Pfizer are 88 per cent efficient in opposition to symptomatic an infection from the Delta variant. Because of this to guard your self from the Delta variant, it is vitally necessary to get two doses.

What is thought concerning the effectiveness of getting AstraZeneca for dose 1 and Moderna or Pfizer for dose 2?

On June 1, the Nationwide Advisory Committee on Immunization (NACI) suggested that Canadians who had AstraZeneca for dose 1 have the choice of Moderna or Pfizer for dose 2.

NACI’s recommendation was partly based mostly on early outcomes from a CombiVacS examine in Spain. CombiVacS enrolled 663 individuals who had AstraZeneca for dose 1. They gave two-thirds of individuals Pfizer for dose 2, and a management group of 232 individuals haven’t acquired a second dose but. Early outcomes discovered {that a} dose 2 utilizing Pfizer elevated the antibodies individuals had after 1 dose of AstraZeneca. Many scientists imagine it is a signal the mix of AstraZeneca and Pfizer (or Moderna) seemingly works effectively.

Not too long ago, a examine in Germany enrolled 340 health-care staff who had AstraZeneca or Pfizer for dose 1 and gave them Pfizer for dose 2. Early outcomes present that the AstraZeneca-Pfizer mixture provides the same immune response in opposition to lots of the variants in comparison with 2 doses of Pfizer. These outcomes would most likely be the identical or comparable if dose 2 had been Moderna.

There’s a bigger examine within the U.Okay. known as Com-COV that enrolled 800 individuals and is researching the advantages and dangers of mixing AstraZeneca and Pfizer. The outcomes might be reported quickly.

What is thought concerning the security of getting Moderna or Pfizer for dose 2?

Scientific research are key to creating certain that vaccines are protected and efficient. Actual world expertise can be necessary. Many international locations all over the world are mixing vaccinations with optimistic results like decrease charges of COVID-19 and fewer individuals needing hospital care. To date, their experiences don’t counsel any extra danger from selecting a distinct vaccine for dose 2.

You might have extra, the identical or fewer short-term unwanted effects from a dose 2 of Moderna or Pfizer in comparison with a dose 1 of AstraZeneca. The Com-COV examine confirmed that individuals who had AstraZeneca adopted by Pfizer 4 weeks later had extra unwanted effects than those that had 2 doses of AstraZeneca. Uncomfortable side effects lasted for one-two days and included tiredness, fever and achy muscle groups. Uncomfortable side effects resolved with relaxation and over-the-counter medicines. Nobody wanted hospital care. The Spanish and German research gave the second dose 8-12 weeks later. The unwanted effects have been comparable for individuals who acquired AstraZeneca for dose 1 and AstraZeneca or Pfizer for dose 2.

Vaccines assist prepare your immune system to acknowledge and struggle the virus that causes COVID-19. Because the immune system begins making antibodies from the vaccine, it’s regular to have unwanted effects like those reported in these research. It’s like being sore after a superb exercise – your immune system is studying a brand new train. These anticipated unwanted effects might final one to a few days.

Each particular person’s immune system is totally different. Some individuals have stronger unwanted effects. Others have milder unwanted effects and a few individuals haven’t any unwanted effects in any respect. You will need to know that these unwanted effects imply the vaccine is working because it ought to.

Why is it OK to ‘combine and match’ vaccine manufacturers?

“Mixing and matching” means you employ one model or vaccine kind for dose 1 and a distinct vaccine model or kind for dose 2. There may be proof for mixing and matching vaccine manufacturers from scientific research and real-world expertise. It may be accomplished when there are issues with provide, when a uncommon however critical facet impact is recognized or to get a stronger immune response. It’s typically protected and efficient.

Just like AstraZeneca, a uncommon however critical facet impact was recognized with the oral polio vaccine within the Nineties. Canadians who wanted 4 doses have been switched to an injectable polio vaccine. This labored effectively and was protected. Hepatitis A additionally makes use of a 2-dose vaccine. Typically, when a model is used for dose 1 however not accessible for dose 2, one other model might be used.

Different international locations are utilizing a mix-and-match technique, too. For instance, in Norway individuals who acquired AstraZeneca for dose 1 might be given Moderna or Pfizer for dose 2.

When is the perfect time to get dose 2?

The unique AstraZeneca, Moderna and Pfizer medical trials separated dose 1 and dose 2 by three-four weeks. That interval was chosen to complete the trials as quick as potential and finish the pandemic.

Newer analysis from the AstraZeneca trials confirmed that folks had higher safety if dose 2 was given nearer to 12 weeks. Earlier analysis on Pfizer discovered {that a} delayed dose of eight weeks may additionally supply higher safety. That is additionally true of many different vaccines. Partially, that’s why NACI suggested Canada to delay the second dose to 16 weeks for all COVID-19 vaccines. A delayed dose 2 would permit extra Canadians to get some safety shortly whereas nonetheless getting the profit from dose 2.

Now that the Delta variant is spreading, it might be higher to get full safety quicker. Having an earlier second dose will end in robust safety a lot sooner, even when ready a number of weeks longer would imply barely stronger safety.

The vaccine you get might depend upon the place or how briskly you wish to get dose 2. For instance, in case you work in a crowded house or dwell in a COVID-19 “hot-spot,” you may wish to get dose 2 as quickly as potential. For those who do business from home, are comparatively remoted and don’t have any private danger elements (for instance, a power illness), it’s possible you’ll really feel you possibly can wait.

If I get Moderna or Pfizer, will I would like greater than two doses?

The NACI steerage for Canada says that you’re “totally immunized” upon getting dose 1 of AstraZeneca and dose 2 of AstraZeneca, Moderna or Pfizer. Two doses of Moderna or Pfizer aren’t wanted in case you already had dose 1 of AstraZeneca. This strategy is being utilized in different international locations as effectively.

Many international locations have journey and exercise restrictions based mostly on vaccination standing, also known as a “vaccine passport.” Every nation may have totally different pointers however lots of them say that two doses of any authorised vaccine is taken into account totally immunized.

Different Issues to Contemplate

Crucial factor is to get dose 2. It may be AstraZeneca, Moderna or Pfizer. As you make your alternative, take into consideration what’s most necessary to you:

How did I really feel after dose 1 of AstraZeneca?

  • Many individuals have been nervous concerning the danger of extreme blood clots and don’t wish to fear once more.
  • Many individuals had unwanted effects akin to a sore arm, fatigue, headache, physique aches and chills.
  • It’s not recognized if there might be extra, the identical or fewer unwanted effects in case you get a dose 2 of Moderna or Pfizer.
  • You could wish to plan for a simple day after dose 2 with any COVID-19 vaccine.

How lengthy will I’ve to attend for dose 2?

  • Canada is getting a big provide of Pfizer and Moderna proper now.
  • Most individuals ought to have the ability to get a dose 2 of a vaccine 12 weeks after dose 1, together with AstraZeneca, Moderna or Pfizer.
  • Adults aged 70 and over might be able to get a dose 2 of AstraZeneca, Moderna or Pfizer now.
  • Adults aged 40-69 might be able to get AstraZeneca now or might have to attend a number of weeks to get Moderna or Pfizer.

How do I determine between Moderna and Pfizer?

  • Moderna and Pfizer are basically the identical vaccine.
  • Each the Moderna and Pfizer vaccines are mRNA (messenger RNA) vaccines.
  • Each Moderna and Pfizer present comparable safety in opposition to COVID-19.
  • Each Moderna and Pfizer have comparable unwanted effects.
  • Pfizer requires colder freezers and is harder to make use of so it’s usually given at giant vaccine centres and busy pharmacies.
  • Moderna is simpler to make use of and could also be accessible at major care clinics and smaller or rural pharmacies.
  • Get the vaccine that’s best or quickest for you.

Being totally vaccinated presents nice immune safety from COVID-19, together with all of the variants studied up to now. For two-dose vaccines like AstraZeneca, Moderna and Pfizer, “totally vaccinated” means getting 2 doses, even when dose 2 is a distinct model than dose 1. The necessary factor to recollect is {that a} second dose with AstraZeneca, Pfizer or Moderna is best than no second dose in any respect.

You probably have questions or want to debate additional, please contact your physician, nurse practitioner, or pharmacist earlier than you e-book your vaccine appointment.


Kate Miller, MD; Division of Household Medication, McMaster College.

Kelly Grindrod, BScPharm, PharmD, MSc; Faculty of Pharmacy, College of Waterloo.

Noah Ivers, MD, PhD; Ladies’s School Hospital-College of Toronto.

Samira Jeimy, MD, PhD, FRCPC; Division of Scientific Immunology and Allergy, Division of Medication, Western College.

Tara Kiran, MD, MSc, CCFP, FCFP; Division of Household and Neighborhood Medication, St. Michael’s Hospital, College of Toronto.

Menaka Pai, MSc, MD, FRCPC; Division of Medication, McMaster College.

Adrian Poon, BA; College of Waterloo.

Vivian Smith, PhD.

Sabina Vohra-Miller, MSc; Unambiguous Science.

Kristen Watt, BScPhm, RPh.

Holly Witteman, PhD; Division of Household & Emergency Medication, Université Laval.

Samantha Yammine, PhD; Science Sam Media.

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