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What’s The Deal With COVID19 Boosters?

What’s The Deal With COVID19 Boosters?


As Sri Lanka rolls out its COVID19 booster program, we break down the answers to your most pressing questions.

Firstly, what is a booster?

A booster is an additional shot of the vaccine given to supplement the protection from the original doses. It is timed to be administered as the protection from original doses wane so you can maintain a good level of immunity for a longer period of time.

But aren’t I good with the two doses I got previously? Why do I need another dose?

A recent Public Health England(4) report detailed how vaccine effectiveness changes with time for those that received two doses of AstraZeneca and two doses of Pfizer.

Twenty weeks after the second dose:

covid19 booster
vaccine effectiveness pfizer

The same study showed there was a greater waning of vaccine effectiveness for the 60+ age group that received AZ.

By administering a booster, especially that of a more efficacious vaccine, we kick into gear the immune response against COVID19 and its variants.

What do variants mean for boosters?

We saw the carnage that was wrecked by the delta variant in Sri Lanka & around the world over the last few months. Vaccination and preventing spread is important in curtailing variants from forming in the first place. However, once they appear, vaccines play a large role in preventing symptomatic sickness, hospitalisations and deaths.

Pfizer and Moderna, the mRNA vaccines, have shown better vaccine effectiveness against the more potent delta variant vs. alpha.

alpha delta variant

When is the booster administered?

Across the world, including in Sri Lanka, the booster is given three months after the second dose of the original regime.

Who can get a COVID booster in Sri Lanka?

At the time of writing, the Ministry of Health is rolling out the booster program for:

  • Healthcare and front line workers
  • Over 60 population
  • Those who are 20 years and above with comorbidities or are immunocompromised (at least after one month after the second dose)

The booster is currently given to those above 60 in the Southern & Western provinces, Anuradhapura and Ampara. They will receive an SMS with the date, time and location of the booster.

Which vaccine is used as a booster in Sri Lanka?

Pfizer/BioNTech mRNA vaccine (30mg dosage) is used as a booster in Sri Lanka. This method of mixing different vaccines (heterologous booster) has been previously used for other vaccines such as Ebola.

Wait, but I got AstraZeneca as my first two doses. Is it safe to mix & match?

Short answer: Yes.

Long answer: In May 2021, a UK trial(3) of 830 participants reported safety data for mix & match vaccines when compared to same type (homologous) vaccines. Though those that received Pfizer after AstraZeneca reported greater intensity of fatigue, headaches and muscle aches – these side effects only lasted 48 hours. There were no hospitalisations or any severe adverse events reported.

What about Sinopharm?

There have been no published studies on mixing mRNA vaccines with Sinopharm. However, Bahrain started boosting those that received two doses of Sinopharm with Pfizer in June.

Are we the only country mixing and matching vaccines?

Nope! Pfizer and Moderna have been approved as booster doses for those that have taken other vaccines in major countries such as the U.K, U.S, Canada and Israel.

Okay, say I get this booster. What does it mean for my immunity against COVID-19?

The Spanish CombiVac trial(2) with 663 people reported in May 2021 that the participants who received a Pfizer booster eight weeks after receiving their first AstraZeneca dose showed a markedly higher level of antibodies than the response generated after two doses of AstraZeneca.

This is expected. When additional doses of a viral vaccine like AZ is administered, the body generates an immune response quickly to destroy the foreign particles. Basically, it becomes good at recognising the virus that it doesn’t allow the vaccine to do its thing – last long enough in the body to actually boost the immune response.

However, by introducing an mRNA vaccine after a viral vaccine, the body is made to work a little harder and longer to recognise the virus. This results in a boosted immune response.

Okay but how many boosters will we need? Will this pandemic ever end?

This too shall pass so the pandemic will end. However, we have a large role to play in this. Our behaviour will dictate whether the pandemic rages on with newer and more potent variants or it gets squashed sooner than later. Variants occur when the virus is allowed to spread so stopping the spread by sticking to COVID19 guidelines is of paramount importance. The less variants, the less need for boosters.

Vaccines save lives and vaccinated people don’t spread the virus as easily as unvaccinated people. So the more people that get vaccinated, the less spread and the sooner we can end this merry go round.

Got more questions? Want to understand whether you should sign yourself or your loved one up for a booster dose? Speak to one of our doctors on oDoc! Download the app today!


  • Booster Shots and Third Doses for COVID19 Vaccines: Everything You Need to Know. (2021)., Johns Hopkins Medicine
  • Callaway, E (2021), Mix-and-match COVID vaccines trigger potent immune response., Nature.
  • Shaw, R et al (2021)., Heterologous prime-boost COVID19 vaccination: initial reactogenicity data., The Lancet., 397:2043-2046
  • Duration of protection of COVID-19 vaccines against clinical disease. (2021) Public Health England
  • Bernal et al (2021)., Effectiveness of COVID-19 vaccines against the Delta variant., NEJM., 385:585-594

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Back to School – A Battle Between Education and COVID-19

Back to School - A Battle Between Education and COVID-19


Students are finally returning to school. But as parents, many are worried about COVID-19 safety. But while preparing to return to school, it is also essential to think about the other ways to keep your children safe and build an environment inclusive of everyone. 

Here are a few tips to help protect your children from this virus.

covid safety children school

If you have any questions regarding your child’s health or would like some medical advice you can consult a paediatrician or a general physician from the comfort of your home via the oDoc app. Click here to download oDoc now.


  1. What Do Students Need This Back-to-School Season?, Raliance (2021)
  2. Be Back-to-School Ready, Weill Cornell Medicine (2021)

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Children, COVID19 and Multisystem Inflammatory Syndrome – The What’s What

Children, COVID19 and Multisystem Inflammatory Syndrome - The What’s What


Parents around the world, including Sri Lanka, have been concerned about Multisystem Inflammatory Syndrome or MIS-C appearing in children who have been diagnosed with COVID19. In this article, we break down what’s known, what remains unknown and the steps to take if you suspect your child could be suffering from MIS-C.

What is MIS-C?

MIS-C is a condition where different parts of the body can become inflamed including the heart, lungs, brain, eyes, kidneys or gastrointestinal tract. 

It appears in children who have had or been around someone who has been diagnosed with COVID19. It’s considered to be a potentially serious condition, developing as a delayed complication of COVID19. Data shows that it usually develops two to six weeks after children have recovered from the virus. It can even develop in those children who were asymptomatic to COVID19. 

What are the symptoms of MIS-C?

Call your regular paediatrician or an on-demand paediatrician or family doctor at anytime on the oDoc app if your child is experiencing:

  • A fever and any of the following symptoms:
    • Abdominal pain
    • Bloodshot eyes
    • Chest tightness/pain
    • Diarrhoea
    • Extra fatigue or feeling unusually weak or dizzy
    • Headache
    • Low blood pressure
    • Neck pain
    • Rash 
    • Vomiting

If your child is showing any of the following signs, please seek emergency care immediately

  • Difficulty in breathing
  • Continuous pain or pressure in the chest
  • Inability to stay awake or alert
  • Pale, grey or blue coloured skin, lips or nail bed

This is not an exhaustive list of symptoms, please call a medical professional immediately if any other signs or symptoms appear that are severe or concerning to you. 

Please call 1990 for the Suwa Seriya ambulance service.

Can MIS-C be treated?

Doctors will conduct diagnostics tests on your child to look for inflammation and other signs of disease. Once diagnosed, doctors will closely monitor your child and use a variety of medications to reduce inflammation and protect the affected organs. 

It is vital to seek medical care at the earliest indication of MIS-C. 

What are the unknowns?

There are still a lot of questions out there such as why do some recovered children develop MIS-C and others do not? What health factors could contribute to MIS-C? 

Scientists are working hard to answer these questions and we will update this blog as and when new research is published. 

And finally…

The best way to protect your child from MIS-C is to protect your household from COVID19, this includes:

  • Getting all adults in the household vaccinated at the first opportunity to do so
  • Continuing to mask when interacting with others from different households
  • Washing hands often with soap and water
  • Conducting play dates within a social bubble and in an outdoor environment

If you are concerned about COVID19 or MIS-C and would like medical advice, please consult a pediatrician or family doctor on the oDoc app. Click here to download the app.


  1. For Parents: Multisystem Inflammatory Syndrome in Children (MIS-C) associated with COVID-19, website (2021)

  2. Multisystem Inflammatory Syndrome in Children (MIS-C), Boston Children’s Hospital (2021)

  3. MIS-C and COVID-19: Rare Inflammatory Syndrome in Kids and Teens, Johns Hopkins Medicine (2021)


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Long COVID: What we know so far

Long COVID: What we know so far

Since May 1st, over 300,000 cases of COVID-19 been diagnosed in Sri Lanka. We are mostly familiar with the short term symptoms of the disease (e.g. fever, cough, sore throat, runny nose to name a few). Most have recovered but ca. 8,700 persons have died at the time of writing. Some have seen symptoms persist for a longer period, a condition globally known as long COVID. In this article, we break down what we know so far about long COVID.

What is long COVID?

The UK’s National Health Service describes long COVID as having symptoms that continue for more than 12 weeks after initial diagnosis which cannot be attributed to another illness.

The UK COVID Symptom study found that 1 in 7 adults experienced symptoms for longer than 4 weeks and 1 in 20 adults experienced symptoms beyond the 8 week mark.

long COVID

What are the common symptoms of long COVID?

There are over 200 symptoms that have been reported that affect various organs in the body from the brain to the skin. Symptoms vary from person to person.

Most common symptoms include:

  • Extreme fatigue
  • Brain fog (problems with memory or concentration)
  • Joint pain
  • Changes to taste or smell
  • Shortness of breath, heart palpitations and chest tightness

Other symptoms range from hallucinations, insomnia, hearing and sight changes, gastrointestinal problems to changes in periods and skin conditions².

Those that experience long COVID have described it as “a storm. One day you can have zero symptoms … then it will just go crazy and as quickly as it hits you it can go.”³

What makes some people prone to long COVID whilst others recover quickly?

The science is still out on exactly why some people suffer for longer. Persons experiencing long COVID are not thought to be infectious but one theory is that the body continues to respond to small amounts of the virus that remains in the body & become reactivated. Another theory is that the infection causes some people’s bodies to go into overdrive, attacking its own tissues.

The COVID symptom study¹ had also found that those who experienced a milder version of COVID19 are more prone to long COVID over an extended period of time.

There is evidence that the following categories of people may be more prone than others:

  • Women
  • Older adults
  • People with pre-existing asthma
  • People who had a wider range of symptoms during their initial illness

Can children get long COVID?

A recent study by King’s College London found that for most children, COVID tends to be a mild, short illness. The 1,500 subject study reported that the average duration of symptoms for a child is six days and fewer than 1 in 50 children are unwell after eight weeks.

How long does it take to recover from long COVID?

Recovery estimates vary but most people with long-COVID are able to live life as relatively normal. However, It is important to get healthcare advice from a trusted professional, listen to your body and rest as much as possible when symptoms flare up.

Are there any treatments available?

Large studies are underway to better understand the nature of this secondary condition. As the 216m persons infected with COVID around the world recover, their experiences help shed light on the disease.

Whilst there are no specific treatments available, the focus is on managing symptoms and enabling a slow return to normal activity.

Nutrient rich foods rich with vitamins & minerals that support the immune system are deemed beneficial and experts encourage patients to eat a holistic, well rounded diet.

Worried you may be suffering from long COVID?

If you are experiencing any new or worsening symptoms, especially 4-8 weeks post your initial COVID-19 diagnosis, speak to a doctor on oDoc. Your doctor will discuss your symptoms and if necessary, order clinical tests to rule out other causes. They will provide guidance on how to best manage your symptoms.

If you are worried or anxious about COVID19 or long COVID, speak to a mental health professional on oDoc.

Click here to download the oDoc app to your mobile device.


  • COVID Symptom Study, 2020 How long does COVID-19 last? ZOE COVID Study, UK
  • Davis, H et al., (2021) Characterizing long COVID in an international cohort: 7 months of symptoms and their impact. The Lancet
  • Guardian, UK., 2020, Lingering and painful: the long and unclear road to coronavirus recovery.
  • COVID Symptom Study, (2020) Do children get long COVID? ZOE Covid Study, UK
  • Molteni et al., (2021).,Illness duration and symptom profile in symptomatic UK school-aged children tested for SARS-CoV-2., The Lancet

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The harsh truth: Children are getting COVID

The harsh truth: Children are getting COVID


As of 9th August 2021, 45,000 children have contracted COVID-19 in Sri Lanka, with around 20,000 under 10 years of age. Some children have had high fever and other severe symptoms that require treatment at hospitals, with Lady Ridgeway Children’s Hospital stating that they have run out of capacity treating COVID infected children.

If you’re a parent or anyone who has young nieces, nephews or cousins, the last thing you want to think about is having these little ones in hospitals, struggling in any sort of way.

What are the long-term effects of children contracting COVID?

Even if children do contract COVID and have healthy enough immune systems to fight off the virus, the long-term effects post-COVID, known as long COVID, should not be taken lightly. Similar to adults with long COVID, children can suffer devastating neurological, physical and psychological issues that can disrupt their schooling, sleep, extracurricular activities and other aspects of life. Symptoms such as fatigue, headaches, brain fog, memory and concentration difficulties, sleep disturbances, ongoing change in smell and taste can creep up even after the child has recovered from COVID.

“The potential impact is huge,” said Dr. Avindra Nath, chief of infections of the nervous system at the National Institute of Neurological Disorders and Stroke who spoke to The New York Times. “I mean, they’re in their formative years. Once you start falling behind, it’s very hard because the kids lose their own self-confidence too. It’s a downward spiral.”

How can you protect the children in your household?

The problem is that young children or teens cannot be vaccinated at this moment. The best solution right now to keep them safe is to get yourself and everyone in your household vaccinated right now if eligible.

Children are at home these days so there is no chance they are contracting the virus from other children. They are most likely getting the virus from their parents or grandparents and others in their household. With the extremely contagious and transmissible Delta variant, if one person in the household contracts COVID, it is highly likely that everyone else in that household, including the children, will get the virus as well.

Studies have shown that vaccinating older adults has decreased the number of COVID-19 cases in young children. A clear example of this was in Israel, where COVID-19 cases in children declined rapidly when adults got vaccinated in large numbers earlier this year.

But don’t vaccinated adults still pass on the virus?

Yes, but vaccinated people are much less likely to get infected with COVID-19, therefore are less likely to pass on the virus to others. Even if they do get infected, vaccinated people clear the virus much faster with a significantly shorter infectious period than the unvaccinated, hence making them much less contagious.

What more can you do to protect the children in your household?

Teach your children the importance of wearing masks over nose & mouth, good hygiene and physical distancing whenever outside the home. It’s a sad reality to subject our kids to this new world but with all these precautions in place, hopefully we can move onto a newer world where our kids can go back to schools and be with their friends safely!

If you have questions about the vaccines and are still on the fence on getting a vaccine, please consult with a doctor on oDoc today.


  • The Best Way to Keep Your Kids Safe From Delta, The Atlantic
  • Kids Struggle With Long COVID, The New York Times
  • Lady Ridgeway Runs Out of Capacity, Daily Mirror

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