COVID-19 is the disease caused by a new coronavirus called SARS-CoV-2. COVID-19 spreads mainly by droplets or aerosols from the nose or mouth of infected person. The onset of symptoms is around 2-14 days. The symptoms of COVID-19 include fever, fatigue, headache, runny nose, sore throat, cough, lost of taste or smell. Some people may experience severe symptoms like pneumonia and death.

 

What is COVID-19 vaccine?

COVID-19 vaccines have various technologies of vaccine manufacturing. The COVID-19 vaccines which are inactivated type or viral vector type are as the following:

• Coronavac^TM (Sinovac), COVILO^TM (Sinopharm) are inactivated vaccine. They work by using killed viral particles of SARS-CoV-2 to expose the body's immune system to the virus.
• COVID-19 Vaccine AstraZeneca^TM, COVISHIED^TM made from genetically engineered adenovirus that causes the common cold in chimpanzees, so it cannot replicate and infect human. The virus can produce SARS-CoV-2-like protein which can trigger human immune system.
• COVID-19 Vaccine Janssen^TM (Johnson & Johnson) is also made from a genetically engineered by adding the gene for the coronavirus spike protein to a modified adenovirus that can enter cells but cannot replicate inside them or cause illness. The virus can produce SARS-CoV-2-like protein which can trigger human immune system.

Efficacy of the vaccine

 

Vaccine	Efficacy data of vaccine
CoronavacTM  (Sinovac)	·     51-67% efficacy against symptomatic COVID-19 cases. ·     85-100% efficacy against symptomatic COVID-19 cases requiring medical treatment. ·     80-100% efficacy against deaths. (Efficacy of vaccine varied by the country of each clinical trial.)
COVILOTM (Sinopharm)	·     78 % efficacy against symptomatic COVID-19 cases. ·     79 % efficacy against hospitalizations
COVID-19 Vaccine AstraZenecaTM, COVISHIELDTM	·     70% efficacy against symptomatic COVID-19 cases. ·     100% efficacy against symptomatic COVID-19 cases requiring hospitalization.
COVID-19 Vaccine JanssenTM (Johnson & Johnson)	·     67% effective overall in preventing moderate-to-severe COVID-19. ·     100% efficacy against hospitalizations and deaths. ·     85% against severe critical COVID-19 cases requiring medical treatment.

 

Who should get the COVID-19 vaccine?

People who are at risk of COVID-19 infection such as medical personnel as well as workers and officials tasked with disease control or are in contact with patients, and people who are at risk of severe COVID-19 disease such as elderly, obesity, and those with lung disease, heart disease, diabetes mellitus, immunocompromised, stroke, cancer, etc.

Each COVID-19 vaccines has indication in different population as the followings:
 

CoronavacTM  (Sinovac)	Indicate for active immunization of individuals 18-59 years old for the prevention of COVID-19.
COVILOTM (Sinopharm) COVID-19 Vaccine AstraZeneca TM, COVISHIELD TM COVID-19 Vaccine JanssenTM (Johnson & Johnson)	Indicate for active immunization of individuals 18 years old or older for the prevention of COVID-19.

The evaluation of available safety and efficacy data in the group of children and adolescents (aged less than 18 years old) has not been established.
In the same way, the safety and efficacy of COVID-19 vaccine in pregnancy and breastfeeding have not been yet established. Breastfeeding and pregnancy after the first 12 weeks could be considered to receive COVID-19 vaccine but after a discussion of the benefits and risks with their healthcare professional.
 

How the COVID 19 vaccine is given?

Vaccines are injected intramuscularly to the upper arm muscle following the schedule as below:
 

COVID-19 Vaccine	Dose and schedule
	Dose (milliliter)	Number of doses	Dosing interval between two doses
CoronavacTM (Sinovac)	0.5	2 doses	2-4 weeks after the first dose.
COVILOTM (Sinopharm)	0.5	2 doses	3-4 weeks after the first dose.
COVID-19 Vaccine AstraZeneca TM, COVISHIELD TM	0.5	2 doses	10-12 weeks after the first dose. (Some current data supports a dosing interval up to 16 weeks).
COVID-19 Vaccine Janssen TM (Johnson & Johnson)	0.5	One single dose	-

It is recommended that individuals complete the vaccination course with the same vaccine because there are no data on the interchangeability of COVID-19 vaccines. The duration of protection has not been yet established.
 

What if people cannot get the COVID-19 vaccine on schedule?

If people miss a scheduled injection, your doctor will decide when to give the missed injection. Please follow the instructions of your doctor, pharmacist or nurse regarding follow-up injection.
 
 

Who should not get COVID-19 vaccine?

• Anyone who has had a life-threatening allergic reaction to COVID-19 vaccine or any component of the vaccine.
• Anyone suffering from an acute severe febrile illness. However, the presence of a minor illness, such as cold, and/or low-grade fever should not delay vaccination.

 

Who should be special precautions for the COVID-19 vaccine?

• Anyone who has immunocompromised disease such as HIV (human immunodeficiency virus), or take a medicine that affects the immune system (such as high-dose corticosteroids or chemotherapy) because it is not known whether individuals with impaired immune responsiveness will elicit the same response as immunocompetent individuals.
• Anyone with thrombocytopenia, any coagulation disorder or to persons on anticoagulation therapy, because bleeding or bruising may occur following an intramuscular administration.

 

What is the common side effects?

The most common side effects after getting the vaccines were pain, swelling, itching or redness at injection site, followed by fatigue, headache, muscle pain, fever, chills and nausea. Most of which are mild or moderate and go away within a few days on their own. No data on long-term side effects.
 
 

Specific side effects of each COVID-19 vaccine

• Coronavac^TM (Sinovac) Most adverse events were mild or moderate in severity. Fever was reported in 2.5% participants after the first dose and 1.8% participants after the second dose of vaccines, no significant difference in proportion between the vaccine and placebo groups.
• COVILO^TM (Sinopharm) has side effects categorized by frequency as the table below:

 
 

Frequency	Side effects
Very common (>1/10)	Injection site: pain, Headache
Common (>1/100 up to 1/10)	Fever, fatigue, myalgia, arthralgia, cough, dyspnea, nausea, diarrhea, pruritus
Uncommon (>1/1000, up to 1/100)	Injection site: redness, swelling, induration, pruritus dizziness, anorexia, vomiting, oropharyngeal pain, dysphagia, running nose, constipation, hypersensitivity
Rare (>1/10000, up to 1/1000)	Erythema, acute allergic reaction, lethargy, drowsiness, difficulty falling asleep, hypoesthesia, limb pain, palpitations, abdominal pain, rash, lymphadenopathy
Very rare ≤1/10,000	Chills, taste dysfunction, loss of taste, paresthesia, tremor, attention disorder, epistaxis, asthma, throat irritation, tonsillitis, blurred vision, hypertension, hypotension

 

• COVID-19 Vaccine AstraZeneca ^TM, COVISHIELD ^TM has side effects categorized by frequency as the table below:

 

Frequency	Side effects
very common (>1/10)	Injection site: tenderness, pain, warmth, pruritus, bruising Headache, nausea, muscle pain, joint pain, fatigue, malaise, feverishness, chills
Common (>1/100, <1/10)	Injection site: swelling, erythema Vomiting, fever
Uncommon (>1/1000, <1/100)	Dizziness, stomach pain, itching, rash, excessive sweating, poor appetite, enlarged lymph node

 

• COVID-19 Vaccine Janssen^TM (Johnson & Johnson) has side effects categorized by frequency as the table below:

 

Frequency	Side effects
Very common (>1/10)	Injection site: pain Headache, nausea, muscle pain, joint pain, fatigue, very tired
Common (>1/100 up to 1/10)	Injection site: swelling, redness Cough, fever, chills , joint pain
Uncommon (>1/1000, up to 1/100)	Rash, sneezing, sore throat, arm or leg pain, back pain, tremor, muscle weakness, feeling weak or generally unwell, excessive sweating
Rare (>1/10000, up to 1/1000)	Allergic reaction, hives
Very rare ≤1/10,000	Blood clot often in unusual locations (e.g., brain, liver, bowel, spleen) in combination with low level of blood platelets
Unknown frequency	Anaphylaxis , severe allergic reaction

 

What if severe side effects occur?

If abnormal symptoms occur such as rash, face or throat swelling, breathing difficulty, arm or leg weakness, please go to the hospital immediately.
 
 

Drug interactions between COVID-19 vaccine and others

COVID-19 vaccines are the new vaccines without data of using COVID vaccines with other type of vaccines. It is recommended to avoid other vaccines at least 2-4 weeks depending on the type of COVID-19 vaccines and concurrent vaccines. To avoid interaction from vaccine injection and immune response disturbance, vaccine injection should be supervised by a doctor.

 

Remarks

• Observe side effects at the hospital at least 30 minutes and then continue to observe side effects at home.
• If you experienced any side effects, please inform the doctor, pharmacist, and medical personnel before getting next COVID-19 vaccine.
• Vaccine cannot protect you entirely from COVID-19 disease but it can protect you from severe COVID-19 disease. Therefore, people who get the COVID-19 vaccine can be infected without symptom or mild symptom. You need to maintain to comply with prevention measure such as social distancing, wearing a face mask, and frequently washing hands.
• Get a vaccine as schedule and keep the vaccine record with you.
• If you have any further question about COVID-19 vaccines, you can ask your doctor, pharmacist or medical personnel.

References

• CoronaVac [package insert].Bangkok: The Government Pharmaceutical Organization; 2021.
• European Medicines Agency. COVID-19 Vaccine AstraZeneca. Available from: https://www.ema.europa.eu/en/documents/product-information/covid-19-vaccine-astrazeneca-product-information-approved-chmp-29-january-2021-pending-endorsement_en.pdf [Accessed 27 May 2021].
• European Medicines Agency. COVID-19 Vaccine Janssen. Available from: https://www.ema.europa.eu/en/documents/product-information/covid-19-vaccine-janssen-epar-product-information_en.pdf [Accessed 27 May 2021].
• Department of Disease Control. COVID-19 Vaccination Guideline in Thailand. Available from: https://online.pubhtml5.com/nqwl/vxcg/#p=1 [Accessed 27 May 2021].
• The Royal Thai College of Obstetricians and Gynaecologists, Announcement on information about pregnancy and breastfeeding and COVID-19 vaccines. Available from: http://www.rtcog.or.th/home/ประกาศ-เรื่อง-การฉีดวัคซ/4976/ [Accessed 27 May 2021].

 
 

Frequently Asked Questions (FAQ) About the COVID-19 Vaccine

General Information About the COVID-19 Vaccine

Q. What is the COVID-19 vaccine?
A: There are currently four main types of the COVID-19 vaccine, classified by the technology used to make them, as follows:

1. mRNA vaccines are made using the genetic material of the virus SARS-CoV-2. When injected into the body this vaccine will cause cells to produce the viral protein. The body will then develop an immune response to this protein by making antibodies.
2. Viral vector vaccines are made from a modified version of a different virus (the vector) and not the one that causes COVID-19. When the vector enters a cell in the body, it produces a spike protein that is only found on the surface of the virus that causes COVID-19. The immune system will then produce antibodies to fight what it believes is an infection.
3. Protein-based vaccines are made from the spike protein of the virus SARS-CoV-2 that triggers an immune response in the body.
4. Inactivated vaccines are made of the inactivated SARS-CoV-2 and when injected, it stimulates the production of antibodies by the immune system.

 
Q: Which COVID-19 vaccines are available in Thailand?
A: Currently there are two COVID-19 vaccines available in Thailand (according to the data available on May 18, 2021):

1. The COVID-19 vaccine from AstraZeneca, which is suitable for those over the age of 18, and given in two doses spaced 10-12 weeks apart.
2. The CoronaVac or Sinovac COVID-19 vaccine, which is an inactivated vaccine that is given to those between 18 and 59 years old. The vaccine is given in two doses spaced 2-4 weeks apart.

 
COVID-19 Vaccinations for Different Groups

Q: Who should receive the COVID-19 vaccine?
A: The goal of vaccination is to reduce severe illness and death from disease and create herd immunity and so it is recommended that the following people receive the vaccination immediately:

1. Frontline health workers and those at high risk of contracting the disease
2. Adults with medical conditions that are stable, such as diabetes, heart and blood vessel disease, chronic renal failure, stroke, hypertension, diseases of the digestive system and liver, HIV (human immunodeficiency virus), cancer, arthritis, lupus, psoriasis, allergies, dementia, paralysis, chronic kidney disease, asthma, chronic obstructive pulmonary disease (COPD), and the elderly may receive the COVID-19 vaccine as the aforementioned indications can lead to severe illness and even death from COVID-19 infection.
3. The general population who have no contraindications to receive the COVID-19 vaccine.

Q: What are the contraindications for the COVID-19 vaccine?
A: Contraindications for the COVID-19 vaccine include:

1. Age under 18 years (there is no data for use in children for the vaccines available in Thailand)
2. Allergy to vaccine components or severe allergy to the first dose of the vaccine
3. COVID-19 infection within the last 3 months
4. A medical condition that is not yet stable or cannot be managed
5. Pregnancy under 12 weeks
6. Fever or illness (vaccine should be given 1-2 weeks after full recovery)
7. Having received any vaccine in the previous 2-4 weeks

 
Q: Can people who are prone to bleeding, who have low or abnormal platelets, and/or who are taking antiplatelets or anticoagulants receive the COVID-19 vaccine?
A: Yes, they can, but it is recommended that a smaller needle (25 or 27) is used in the muscle of the upper arm. After the vaccine, pressure should be placed on the site for approximately 5 minutes. Ice or a cold gel compress may be placed on the site after the vaccination. (Referencing the Thai Society of Hematology, May 18, 2021)
 
Q: Can anyone under the age of 18 receives the COVID-19 vaccine?
A: There are currently no studies of the COVID-19 vaccine in those under 18, but most vaccine manufacturers recommend their vaccine for those 18 and older, with the exception of the Pfizer-BioNTech vaccine, which is recommended for those 12 and older.
 
Q: Can pregnant, lactating, and menstruating people receive the COVID-19 vaccine?
A: There are currently no studies regarding the COVID-19 vaccine and pregnancy, but the Thai Department of Health recommends that pregnant people be vaccinated for COVID-19 after 12 weeks of gestation. It is important to consult a doctor to determine the risks and benefits of receiving the vaccine during pregnancy and potential side effects. Lactating and menstruating people can receive the COVID-19 vaccine just as any other individual.
 
Q: If I am waiting for the result of a COVID-19 test, can I receive the COVID-19 vaccine?
A: You should wait for the result of the COVID-19 test. If it is negative, you may receive the vaccine immediately. If the test is positive, you must wait 3-6 months for full recovery before receiving the vaccine.
 
Q: If I have had COVID-19 before do I still need the vaccine?
A: Even if you have had COVID-19 before and have some immunity to the virus, there is currently no information regarding the duration of this immunity and there is still the chance for reinfection. So even if you have had COVID-19 before, it is recommended that you are vaccinated. Please wait 3-6 months after when you were infected to get the vaccine. There is no need for a COVID-19 test before the vaccine as there is no danger from the vaccine even if you have COVID-19. Only one dose may be administered in this case.
 
Efficacy and Safety

Q: How many days after receiving the vaccine will I be immune to COVID-19?
A: The highest immunity is achieved 14-28 days after the second dose of the vaccine so it is important that you receive both doses of the vaccine for the highest efficacy.
 
Q: How long will the immunity last and will booster shots be required?
A: Currently there is no information about the duration of immunity to COVID-19 after receiving the vaccine. Preliminary research shows that the vaccine is protective beyond 6 months. Information about boosters is currently unavailable and we will need to wait for the recommendations of experts in the future.
 
Q: If I am vaccinated and become infected with COVID-19, will the symptoms be milder?
A: The COVID-19 vaccine may not absolutely prevent infection, but it is highly effective in preventing severe disease. So even if you are vaccinated you can become infected with COVID-19 but will likely have mild symptoms or none at all, and it is important to continue measures to prevent infection, including wearing a mask, maintaining physical distance, and washing hands often.
 
Q: If I am vaccinated, can I become infected with COVID-19 and will I be contagious?
A:  The COVID-19 vaccine may not absolutely prevent infection so even if you are vaccinated, you can become infected with COVID-19, but will likely have mild symptoms or none at all. It is important to continue measures to prevent infection, including wearing a mask, maintaining physical distance, and washing hands often. If you come into contact with someone that is infected with COVID-19, please self-isolate and see your doctor for testing and treatment as necessary.
 
Q: Can the vaccine protect me from variants of the virus?
A: The vaccines available now were manufactured for the original virus that caused COVID-19 and may not be as effective against variants of that virus. However, the impact of variants on the efficacy of the current vaccines must be further studied and different vaccines may be required as the virus continues to mutate, similar to the vaccine for influenza.
 
Q: What are the side effects of the COVID-19 vaccine?
A: From research of the various COVID-19 vaccines currently available, the most common symptoms are specific to the injection site, such as pain, swelling, and redness at the site. Other possible side effects include fatigue, headache, body ache, fever, and nausea. For the most part side effects are mild and disappear on their own within 1-2 days, but vaccines can cause severe allergic reactions. Thus, you will be observed by medical professionals for at least 30 minutes after you receive the vaccine. If you experience any adverse effects from the vaccine or experience symptoms that may be related to the vaccine, please contact your doctor immediately. There is currently no information about the long-term effects of the COVID-19 vaccine.
 
COVID-19 Vaccine and Other Vaccines

Q: Can I receive other vaccines, such as those for influenza, rabies, DTap (Diphtheria, Tetanus, Pertussis), MMR (Measles, Mumps, Rubella), and/or HPV (Human Papillomavirus) at the same time as I do the COVID-19 vaccine? If not, how long should I wait between vaccines?
A: The COVID-19 vaccine is very new and there are no studies about the efficacy and safety of the vaccine when combined with other vaccines so it is not recommended that you receive other vaccines at the same time. It is recommended you wait at least 2-4 weeks between receiving the COVID-19 vaccine and another vaccine, but this may vary according to the type of COVID-19 vaccine you get as well as the other vaccines you need. This is to prevent any adverse effects of receiving multiple vaccines at one time and to ensure the best immune response to each vaccine. However, if a vaccine is necessary, such as rabies if you have been bitten by an animal, then the benefits outweigh the risks.
 
Q: What if I receive the COVID-19 vaccine and then realize I received another vaccine less than 14 days before? What should I do?
A: You may count that first COVID-19 vaccine as the first dose and should receive the second dose as appropriate.
 
Q: Are the different brands/types of COVID-19 vaccines interchangeable?
A: There is currently no information about using multiple brands/types of COVID-19 vaccine except when there is a severe allergy to the first dose of a certain brand/type. The second dose, in this case, must be of a different type of COVID-19 vaccine. Your doctor and pharmacist will determine if your allergy is severe enough to warrant a different vaccine.
 
Q: If I have received the two doses of the COVID-19 vaccine, can I receive a different brand/type in the future, such as Pfizer-BioNTech or Moderna?
A: It is recommended that you receive both doses of the same brand/type of COVID-19 vaccine. If a booster is required in the future, more recommendations will be issued, including the brand/type of vaccine you can get and how long you need to wait between the two. There is simply not enough information at the moment.
 
Recommendations for Before and After Getting the COVID-19 Vaccine

Q: How should I prepare for the vaccine?
A: Before receiving your vaccine:

1. Get plenty of rest the night before.
2. Eat normally but avoid caffeine and cigarettes at least 2 hours before the vaccine. Drink plenty of water.
3. If you have a fever or are ill, please postpone your appointment. If you have a mild cold and no fever, you can still get the vaccine.
4. Prepare your identification card/passport and your appointment confirmation page on the MorPhrom app or the SMS sent by the hospital to present at the registration point when you arrive.

 
Q: What should I do after receiving the vaccine?
A: After receiving your vaccine:

1. You will be observed for 30 minutes for any side effects.
2. Drink plenty of water.
3. If you experience fever or body aches you may take 500 milligrams of paracetamol every 6 hours as needed. (Please avoid non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, Celebrex, or Arcoxia.)
4. Avoid strenuous exercise for a couple of days after receiving your vaccine. Get plenty of rest as needed.
5. Monitor for any severe allergic reaction, such as hives, swelling of the face or neck, difficulty breathing, heart palpitations, dizziness, fatigue, or weakness in the arms and legs. If you experience any of these, please go to the hospital immediately.

 
Q: After receiving the COVID-19 vaccine do I still need to wear a mask and continue measures to prevent infection?
A: Since the COVID-19 vaccine does not absolutely prevent infection, even with the vaccine you can become infected and have mild or no symptoms. The vaccine will prevent severe symptoms. So it is important to continue to wear a mask, wash your hands, maintain physical distance, and self-isolate if you have come into contact with someone who has COVID-19. If you are at risk of contracting COVID-19 please see your doctor immediately for diagnosis and treatment as appropriate.
 
Q: After receiving the COVID-19 vaccine, can I donate blood?
A: The Thai Red Cross Society recommends waiting one week after receiving the vaccine to donate blood, but if you experience any side effects from the vaccine, wait one to two weeks until you are fully recovered (as of May 21, 2021).