Explainer: COVID-19 vaccines in Hong Kong

As the vaccine rollout gathers momentum, confusion and misleading claims about the effectiveness, side effects and safety of different vaccines continue to abound.

Hong Kong has designated vaccination centers in various parts of the city.

As of February 2021, the Hong Kong government has purchased a total of 22.5 million COVID-19 vaccine doses, 7.5 million from each three suppliers; Fosun Pharma/BioNTech, AstraZeneca/Oxford and Sinovac.

Another 300,000 doses of BioNTech vaccine were shipped to Hong Kong after packaging defects of the vial caps were found in the first batch.

BioNTech developed Comirnaty, AstraZeneca produced COVID-19 Vaccine AstraZeneca and Sinovac is behind the CoronaVac vaccine.

The first rollout began on Feb. 26, with the Sinovac vaccination drive. The vaccination with BioNTech began on March 10, while the AstraZeneca vaccine was initially expected to be available in Hong Kong mid-year.

However, on Apr. 5, Health Secretary Sophia Chan said in the Legislative Council that the government will delay shipments of 7.5 million doses of AstraZeneca’s Covid-19 vaccine this year, as she believes Hong Kong already had sufficient supply of vaccines and the government is planning to purchase a new type of vaccine that offers better protection.

As the vaccine rollout gathers momentum, confusion and misleading claims about the effectiveness, side effects and safety of different vaccines continue to abound.

Annie Lab provides the answers to some of the most pressing questions about the vaccination program rolled out in Hong Kong in this explainer.

There have been reports about medical authorities probing the deaths of people with underlying illnesses who took the jab. Has a correlation between vaccination and the deaths of those who took the jab been established by medical experts?

In Hong Kong, the elderly and those with immune systems weakened by other factors have been prioritized for vaccination, as these portions of the populace are more likely to develop severe symptoms if they are infected with COVID-19. These people also have a higher overall mortality rate from any source.

As a result, it may appear that the raised mortality rate of those who received the jab is a consequence of the vaccination itself, rather than reflecting the higher mortality rate inherent to the vulnerable groups prioritized for vaccination.

As part of standard practice, the Hong Kong government also tracks overall trends in mortality rates and investigates cases of deaths that occur shortly after vaccination to ascertain whether there is a causal link.

The body which looks into cases of severe adverse reactions following vaccination is the Expert Committee on Clinical Events Assessment Following COVID-19 Immunisation. The committee will assess if there are underlying risk factors that may increase the mortality rate independent of whether the deceased has been vaccinated.

An example of this can be seen in the 63-year old man who died of a heart attack in Hong Kong on Feb. 28 after receiving the Sinovac vaccine.

The Expert Committee said in its preliminary report on March 3 that the Sinovac vaccine is not directly linked to the death as, independent of his vaccinated status, the man presented four major risk factors for coronary artery disease; high blood pressure, hyperlipidemia, a smoking habit and high blood glucose levels.

Ho Pak-leung, the head of the University of Hong Kong Center for Infection, explained in his Facebook post that regular “life events” naturally occur, such as strokes and deaths, especially with the high-risk groups of elderly care home residents.

The microbiologist said there was no observable difference in the numbers for serious adverse events between the BioNTech vaccine and saltwater as the placebo, and there were deaths in the placebo group as well in the Phase III trial — one from a myocardial infarction, one from a stroke and two with unknown reasons.

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Why are children not eligible to get the Sinovac, BioNTech and AstraZeneca jabs?

The Centre for Health Protection (CHP) said that Sinovac is not recommended for children under 18 years old, the same with AstraZeneca, but the latter can be given to youths, following consultation with doctors about its risks and benefits as well as individuals’ clinical conditions.

BioNTech, on the other hand, is recommended for those aged 16 and older.

The CHP relied on the report from these bodies for these recommendations: the Scientific Committee on Emerging and Zoonotic Diseases (SCEZD), the Scientific Committee on Vaccine Preventable Diseases (SCVPD), and the Expert Advisory Panel to Chief Executive (EAP).

The joint committee of SCEZD and the SCVPD said in their report on Jan.7 that their recommendations were based on the available safety and efficacy data for BioNTech and AstraZeneca.

The Advisory Panel on COVID-19 Vaccines, in its evaluation of BioNTech vaccine’s safety, efficacy and quality, said that the benefits of vaccinating young people aged 16 and above “outweigh” the risks.

Information on the appropriateness and safety of vaccines for children are often determined in clinical trials conducted after those for adults. Manufacturers call this “age de-escalation,” a strategy where clinical trials involving children are only conducted after the efficacy rate for adults has already been ascertained.

How do those three expert bodies work together in Hong Kong?

SCEZD and SCVPD work as a joint committee in COVID-19 Vaccination Programme to review and develop strategies to protect the community from infectious diseases.

Meanwhile, the Advisory Panel on COVID-19 Vaccines, another organization providing expert opinion for the territory-wide vaccination programme, has its members appointed by the Chief Executive in Jan 2020.

The Advisory Panel chaired by convenor Professor Wallace Lau Chak-sing was set up to “advise the Secretary for Food and Health on the authorization and administration of a vaccine”.

Members of the Advisory Panel are experts from the areas of public health, infectious diseases, immunology and more.

Have Hong Kong authorities given an explanation why the Sinovac vaccine is given to people over 60 when in mainland China the domestically-produced vaccines is given only to people aged 18-59?

Many social media users have raised questions on the different recommendations made by the Hong Kong government and the mainland authorities for inoculating people aged 60 and above with Sinovac.

Hong Kong has allowed those 60 and above to be vaccinated with the Chinese-made vaccine since February, while the mainland has only authorized it starting in March.

On Feb. 9, three prominent committees including the SCEZD – which investigates the efficacies of all kinds of vaccines that will be used in Hong Kong – published the Consensus Interim Recommendations on the Use of CoronaVac in Hong Kong.

The experts believe “the benefit of using CoronaVac generally exceeds the risk of not using any vaccines in persons aged 60 or above.” As they reviewed Sinovac’s data and latest scientific evidence, they said “Phase I and II data on individuals aged 60 or above showed that the vaccine is safe and immunogenic,” but also mentioned that there is limited or not enough efficacy data in the Phase III clinical trials because of the small sample size.

Professor Ivan Hung Fan-ngai, a member of the Advisory Panel on COVID-19 Vaccines, said in a radio program that China’s new cases have remained at a low level for an extended period. He believed China has a different vaccination strategy from Hong Kong, as the former targets the younger generation with a more active lifestyle.

On the other hand, Hong Kong went through the third wave with many senior citizens and people with chronic diseases being affected the most. Hung said that’s why they were identified as one of the priority groups for vaccination.

Secretary for the Civil Service Patrick Nip, who is responsible for the vaccination campaign, said that elderly people from other places have also been vaccinated by Sinovac. For example, Indonesia, Turkey and Brazil have administered the Sinovac vaccine for people aged 60 and over.

In China, the Beijing Center for Diseases Prevention and Control said on March 1 that they have started to inoculate people aged 60 and above with Sinovac. Chinese experts said the elderly have earlier been excluded from the priority list that focuses on people working in areas where imported cases are expected to emerge.

According to a statement published by the Chinese government, the age group that can be vaccinated will be expanded further when related scientific evidence and data become more concrete and technologies are more advanced.

In Hong Kong, those above the age of 70 are three times more likely to be infected and suffer fatal complications compared to younger ones, according to the information posted by the HKU School of Medicine. There have been COVID-19 outbreaks in elderly homes in the city.

The experts quoted by Global Times said “China is taking a cautious approach in vaccinating elderly people, especially after reports of seniors dying after receiving Pfizer’s vaccine in Europe raised wide concerns” although “there has been no evidence directly linking the deaths to the Pfizer vaccine.”

Related medical research papers:

Does getting vaccinated mean that you cannot get infected with the coronavirus or does it only protect you from developing severe and critical conditions?

In general, after vaccination, the body will take time to build immunity against the coronavirus. One could still get infected after receiving a single dose or even the second dose. The time frame to be considered fully inoculated can vary from seven days to more than 14 days after the second dose, depending on the vaccine.

According to the Hong Kong government’s factsheet for the vaccines, people who took the Sinovac jab can be protected effectively 14 days after their second dose while for those who were inoculated with the BioNTech jab, it will take seven days after the second dose.

On the other hand, available information on AstraZeneca says it takes 15 or more days for the vaccine to provide optimal protection. The second dose was given four weeks after the first dose.

Additionally, no vaccine will provide a 100% protection against COVID-19. There is still a chance, albeit one much smaller, of getting infected with the virus and also developing symptoms.However, all vaccines that are available to Hong Kong citizens: BioNTech, AstraZeneca and Sinovac, have been shown to provide good protection against severe and critical infection.

Whether the vaccines will provide long-lasting immunity against COVID-19 or frequent booster shots will be needed remains to be seen. Not enough time has passed for data to be available to address this question.

What side effects of the vaccine are actually very common and should not be worrisome?


A note on the recent information about cases of blood clots: The European Medicines Agency (EMA) stated that unusual cases of blood clots accompanied by low platelet count should be listed as a very rare side effect of the AstraZeneca vaccine.

The decision was made after the agency conducted a detailed review of 62 cases of cerebral venous sinus thrombosis, a blood clot in the brain that is rare, and 24 cases of splanchnic vein thrombosis, an abdominal blood clot. Eighteen of those cases were fatal. The number of cases was seen among 25 million vaccinated people in Europe and the UK.

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What are the signs and symptoms of an allergic reaction to the COVID vaccine? How serious are these reactions?

Most serious reactions to the vaccine are a result of an allergic reaction to one of the ingredients, and should be immediately reported. Signs of an allergic response include:

  • Hives or rash
  • Shortness of breath
  • Tightness of chest
  • Swollen tongue or lips
  • Confusion or anxiety
  • Anaphylaxis (Narrowed airway inhibiting breathing)

According to the U.S. clinical trial for BioNTech, 71% of allergic responses to the vaccine occur within minutes of injection. Under the COVID-19 vaccination programme in Hong Kong, to observe any signs of allergic or adverse reaction after taking the BioNTech vaccine, citizens are required to stay for 15 minutes, or 30 minutes if they have experienced immediate allergic reaction to other vaccines or anaphylaxis due to any cause; also 30 minutes for those who take Sinovac.

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