What is known about the AstraZeneca COVID-19 vaccine (in use overseas) and blood clots?

A very rare clotting disorder has been reported overseas following vaccination with viral vector COVID-19 vaccines in younger adults.

A very rare and new type of adverse event has been observed following vaccination with the AstraZeneca, and more recently the Janssen, viral vector COVID-19 vaccines overseas (including Australia). Although, the reason why this may occur is unknown, it has been proposed the vaccine can induce an immune response where the body incorrectly attacks its own cells to make platelets very sticky. This results in the formation of blood clots in unusual places such as the brain or abdomen. This is similar to a recognised side effect of heparin, a commonly used medication used in hospital.

The unusual characteristic of this type of clotting disorder (thrombosis) is that it is also associated with bleeding due to a lack of platelets in the blood (thrombocytopenia) - the sticky platelets clump together to form clots and this attracts more platelets from the blood - named thrombosis with thrombocytopenia syndrome (TTS). The only risk factor that has been identified so far is age - most cases have occurred in adults aged under 50 years. See the Brighton collaboration for the interim case definition.

This is a very rare event (around 7-10 cases per million doses in those aged under 50 years) and the risk from COVID-19 is significantly higher than the risk of TTS. For this reason, regulatory authorities overseas are weighing up the benefit and potential risk of this vaccine and some have advised age related precautions.

A MedSafe review, published 27 April, finds there is no current evidence of risk associated with the Comirnaty (Pfizer/BioNTech) vaccine and blood clots.

The AstraZeneca COVID-19 vaccine is not yet licenced for use in New Zealand.

To find out more about how vaccine safety is monitored and the risk of blood clots from COVID-19, COVID-19 vaccines and other causes, see this commentary.

References:
https://www.ema.europa.eu/en/news/astrazenecas-covid-19-vaccine-ema-fin…
https://www.gov.uk/government/publications/covid-19-vaccination-and-blo…

https://www.who.int/news/item/16-04-2021-global-advisory-committee-on-v…-(vaxzevria-and-covishield)

Why has the Janssen COVID-19 vaccine roll out been paused in some countries internationally?

Out of an abundance of caution, the roll out of the Janssen COVID-19 vaccine has been paused while further information on rare unusual clotting abnormalities can be collected.

As of 12 April 2021, six cases of abnormal clotting were reported to the Vaccine Adverse Event Reporting System (VAERS) in the US. While this is only a small number compared to the ~6.8 million doses administered, it is important all information is appropriately reviewed and this pause gives scientists the opportunity to do so. In the New Zealand setting, the only vaccine which has been approved for use is the Pfizer-BioNTech COVID-19 vaccine. There have been no reports of this particular clotting concern following 97.9 million doses administered of the Pfizer-BioNTech COVID-19 vaccine. Medsafe will carefully evaluate all the available and emerging data before approval to use can be given.

A MedSafe review, published 27 April, finds there is no current evidence of risk associated with the Comirnaty (Pfizer/BioNTech) vaccine and blood clots.

Reference: 
https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-04/03-…

Can I have a COVID-19 vaccination before a CT scan?

It is important to advise your oncologist or radiographer if you have received the COVID-19 vaccine recently. This is because the vaccine can cause the lymph nodes in your armpit and neck to swell which can be detected by CT scans used to diagnose and monitor cancers.

This is particularly detected by FDG PET/CT scans, in which you are given a contrast medium containing a type of radioactive sugar that is taken up by active cells. When an immune response to a vaccine takes place, the cells in the lymph nodes near the injection site become very active and take up a lot of this sugar. Depending on the type of cancer, you may be able to request the injection on the opposite side to your tumour. If possible, have the vaccination at least 2 weeks before a scheduled scan or as soon as you can afterwards. Do not delay any treatment.

COVID-19 vaccine may cause swelling of local lymph nodes. Does this affect mammogram results?

When you attend a mammogram, it is recommended that you mention to your doctor or radiographer that you have had a COVID-19 vaccination recently.

This is because occasionally the vaccine can cause swelling of the lymph nodes in the arm pit near to the injection-site. This usually settles after a few days after vaccination but may be detectable on a mammogram for up to a few weeks. In this case, it is advised to monitor such lymph node changes for at least 6 weeks after vaccination. You do not need to delay your vaccination or your mammogram.

Click this link for further information from BreastScreen Aotearoa.

Can I receive the COVID-19 vaccine even though I have a compromised immune system or am receiving treatment for cancer?

Many people take medication that suppresses their immune system, especially for the treatment of cancer, severe asthma, autoimmune diseases or following organ transplantation, or have medical conditions that can affect the immune system, such as HIV infection or kidney failure.

These conditions put you at increased risk from COVID-19, and although you may not respond as strongly to the vaccine as someone with a fully functioning immune system, it is safe for you received COVID-19 vaccine and it will provide some protection against COVID-19, particularly against severe and life-threatening disease.

It is important and safe for those receiving active treatment with immunosuppressive medications to have the COVID-19 vaccine. If you are severely immunocompromised, it is recommended to talk to your GP or specialist to discuss the optimal timing for vaccination before the vaccine appointment. Ideally, vaccination should be conducted prior to any planned immunosuppression.

It is also important for the people around you, in your household, to have the vaccine when it is offered to them to widen your protection.


For information about Cancer care and COVID-19 vaccine see Te Aho o Te Kahu (Cancer Control Agency) information here.

Can I have the COVID-19 vaccine if I am allergic to latex?

Comirnaty™ is latex-free. The vial stopper is made with synthetic rubber (bromobutyl), not natural rubber latex.

How are COVID-19 vaccines authorised in New Zealand?

All medicines approved for use in New Zealand, including vaccines, go through strict review by Medsafe to make sure they meet local and international safety and efficacy guidelines.

Once Medsafe has reviewed all available data, it makes a recommendation to the NZ Government as to whether a medicine can be granted approval in New Zealand. More comprehensive information on this process is available on the Medsafe website.

Vaccinations against COVID-19 using the mRNA COVID-19 vaccine, Comirnaty™ (from Pfizer/BioNTech)  have begun. Currently, vaccinations are being given to those at highest risk of exposure to SARS-CoV-2 (the virus that causes COVID-19) and their close household contacts. There will be sufficient doses of this vaccine for everyone in New Zealand. See here for the current vaccine roll-out plan.

The exact date when other vaccines will be available in New Zealand is unknown. Their arrival depends on:

  • Data being available to review, particularly in relation to safety and effectiveness 
  • When Medsafe approval is granted
  • When the vaccine can arrive in New Zealand. 
  • To obtain approval for use in New Zealand, each vaccine needs to meet strictly defined safety and efficacy criteria.

The mRNA COVID-19 vaccine by Pfizer/BioNTech was granted provisional approval for use in New Zealand on 3 February 2021. This means that it has been approved for use in a defined group and on the condition that Medsafe continues to receive and review further data about this vaccine’s safety and effectiveness. Click here to find out more.

This approval differs from that granted in other countries, such as the US, UK and in Europe, in which these vaccines were granted ‘emergency-use approval’ based on early data and an urgent need to start vaccinating soon as safely possible. New Zealand has been fortunate to be able to wait, while receiving the most current clinical trial and post-licensure data, to make the decision to approve the use of this vaccine. Once sufficient data has been obtained, it is likely that Medsafe will convert the provisional consent to full consent in due course.

Watch this video from the Ministry of Health with Dr Ashley Bloomfield and MedSafe's Chris James for more on the vaccine approval process in New Zealand. 
 

What side effects may be expected after vaccination?

The most common responses to the COVID-19 vaccine are injection-site reactions (sore arm for example) and general symptoms such as ‘flu-like’ illness, headache, chills, tiredness, nausea, fever, dizziness, weakness or aching muscles.

Generally, these potential responses happen within a day or two after the vaccination and are not associated with more serious or lasting illness. These types of reactions reflect the normal immune response to this vaccine. Not everyone experiences this type of response. They are more likely after the second dose and tend to resolve within a day or two. Pain relief, such as paracetamol or ibuprofen, is not recommended to be taken before having the vaccine but can be used after it if required. 

In addition, as with any vaccine or medicine, there is a risk of allergic reactions shortly after the vaccinations. Because of this people should wait at a vaccination centre as instructed after having their vaccine. Those with previous allergic reactions or anaphylaxis should tell their vaccinator before going ahead.  

For more information about what to expect after the vaccination see the Ministry of Health's website. 

Monitoring for adverse reactions and side effects is being conducted in New Zealand and worldwide. Vaccine recipients and their health care providers are encouraged to report possible side effects to CARM (Centre for Adverse Reactions Monitoring). See here for the latest Adverse Events following Immunisation report from Medsafe on Comirnaty 
 

Is the Comirnaty vaccine safe and effective for people living with HIV?

The vaccine has been through rigorous testing to ensure safety and efficacy and is now being used widely overseas without any serious concerns appearing. People with HIV were included in clinical trials though efficacy and safety data specific to this group are not yet available.

With some vaccines people living with HIV can produce a weaker immune response. People living with HIV are encouraged to be vaccinated. People with HIV were included in clinical trials for the Pfizer vaccine, although the data specific to this group is not yet available there are no safety concerns.

Based on what we know about people living with HIV and their response to other vaccines:

  • those with a suppressed viral load are likely to have some protection from the COVID-19 vaccine
  • they may have a weaker response to some vaccines, including the COVID-19 vaccine

For people who are newly diagnosed and starting HIV treatment are advised to take advice from their specialist about the timing of their vaccination. Any medication being taken for HIV is not expected to change how effectiveness of the COVID-19 vaccine. The vaccine will not affect HIV medications.​

Will children receive a COVID-19 vaccination?

Medsafe has not approved a COVID-19 vaccine for use in children under the age of 16 as yet.

Further research with vaccine trials enrolling children is underway overseas. Initial data in 12-15 year-olds looks promising, with excellent efficacy and a similar safety profile to that seen in adults. Read this Stuff article with IMAC’s Dr Emma Best offering some helpful ideas on how to approach the topic of COVID-19 and vaccines with children.

Can COVID-19 vaccines be safely given to frail and elderly people?

There are no safety concerns around giving COVID-19 vaccine to older and frail adults. Multiple COVID-19 vaccine candidates have shown to protect against severe disease in older age groups.

A single dose of COVID-19 vaccine substantially reduced (over 70%) the risk of COVID-19-related hospitalisation in elderly, frail patients with extensive co-existing conditions in the UK. By 2 weeks after the second dose effectiveness against symptomatic COVID-19 in adults aged over 70 years was 85-93%. This is important, as increasing age is a risk factor for severe COVID-19.

Following reports of deaths of frail, elderly adults in residential care facilities after COVID-19 vaccination, independent reviews by both the CDC and the WHO concluded that the mortality rate in this population is typically high and a substantial number of deaths will occur coincidentally following vaccination. For further information, click here.

COVID-19 vaccines in pregnancy and breastfeeding

Pregnant people are encouraged to be vaccinated against COVID-19 at any stage of pregnancy.

In pregnancy, the risk of severe COVID-19 complications is much higher than in people who are not pregnant. The updated recommendation aligns with recommendations in other countries and is based on international evidence from a large number of people who have already received mRNA COVID vaccines when pregnant and no additional safety concerns have been shown. There is also increasing evidence that antibodies made by the mother after vaccination are shared with the baby in the cord blood that are likely to also protect her newborn baby against COVID-19.

As with all vaccines on the New Zealand Immunisation Schedule, there are no safety concerns about giving mRNA COVID-19 vaccine to women who are breastfeeding and by being vaccinated, mothers can provide some protection against COVID-19 for their babies in breastmilk.

Please refer to the Immunisation Advisory Centre's COVID-19 vaccination in pregnancy fact sheet for more information.

Reference

Shimabukuro TT, Kim SY, Myers TR, et al. Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons. N Engl J Med. 2021 DOI: 10.1056/NEJMoa21049