COVID, Vaccines

COVID-19 Vaccine: Do You Need It Even After Surviving COVID-19?

Author Chandana Balasubramanian , 18-Aug-2021

Table of contents

Brown t-shirt with 'I got my COVID vaccine' sticker on the pocket

“Should I get the COVID-19 vaccine even if I had COVID?” The answer is yes. Getting COVID-19 in the past is not a guarantee against reinfection.

An August 2021 study out of Kentucky, USA, studied hundreds of residents and found that unvaccinated survivors of COVID-19 had more than double the risk of getting reinfected with COVID-19 compared to the vaccinated group of people. Public health officials, medical professionals, and infectious disease experts worldwide continue to urge more people to get vaccinated as soon as possible. But some individuals who recovered from COVID-19 want to know why.

Wearing safety gear during on-ground combat will not prevent all adverse events. The gear is designed to prioritize and protect a soldier’s brain, heart, spine, and other vital organs from damage. The vaccines are meant to work the same way.

To those on the fence, the decision to get vaccinated or not requires more information. Queries from unvaccinated COVID-19 survivors include:

  • If you already had COVID-19, why are you not protected for life against the virus? After all, with a chickenpox infection, you get lifelong immunity.
  • If people who are vaccinated can still get infected with the Delta variant, why do we need the vaccine?
  • COVID-19 vaccines are currently approved for emergency use. Is this safe?
  • Which COVID-19 vaccine offers maximum protection against COVID-19 and variants like Delta?

Here are answers to these questions to help you choose.

Natural Immunity After COVID-19 Varies Widely from Person to Person. Vaccine Immunity is More Consistent.

Natural immunity from a COVID-19 infection is expected to last 90 days or more in most people. However, the strength of resistance built against COVID-19 varies widely from person to person. It is based on many factors, including viral load (the amount of virus in an infected person’s blood). People who had a light viral load the first time around may not be protected against reinfection. On the other hand, our immune response to the COVID-19 vaccine is more consistent. This is why you are encouraged to get vaccinated even if you had COVID-19.

Different pathogens trigger unique immune responses. The chickenpox virus (Varicella zoster) triggers the production of antibodies with lifelong memories that protect us against reinfection. COVID-19 is new, and so far, there is no data to suggest it offers immunity for life. With the COVID-19 mRNA vaccines, your body gets exposed to a harmless piece of the COVID-19 virus, the spike protein, which is just enough to train our immune system to learn how to fight this particular pathogen.

And for those previously infected with COVID-19, the vaccine can act as added protection, which is necessary to fight emerging variants.

New coronavirus delta variant covid. India mutation of SARS CoV 2, 2019 nCoV new version 2020 2021. Coronavirus new strain. 3D Illustration of viruses with microscope view of sliced virus

The Delta Variant is a Different Beast; Natural Immunity Needs All the Help it Can Get.

The B.1.617.2 variant, or Delta, is significantly more contagious than the original COVID-19 virus from 2020 and all other existing variants. It is also more likely to cause severe disease and death by breaking through our natural immunity and even vaccine-related protections. This applies even if you recovered from COVID-19 in the past.

With the original COVID-19, symptoms took 7 to 14 days to appear. The Delta variant launches its attack on our body much faster. Symptoms could appear within two to three days – which means our immune system has less time to prepare. Additionally, people infected with the Delta variant carry 1000 times more viruses than the original COVID-19. The vaccines can boost our natural immunity to strengthen our resistance against the new COVID-19 variants, including the insidious Delta.

It is important to note that the COVID-19 vaccines have proven effective at protecting against severe illness and death. It is still possible to get infected after being vaccinated. But if you are vaccinated, you will most likely experience milder symptoms without extreme damage to your lungs and other organs. In the United States, 97% of hospitalizations from Delta and 99% of associated deaths are due to unvaccinated individuals. These percentages are based on data from January to June and will be updated based on the impact of Delta.

Keep in mind that you are considered fully vaccinated two weeks after your second dose for two-dose vaccines or after one shot for a single-dose vaccine. Even after getting vaccinated, it is advisable to continue following recommended safety protocols.

According to Stephen Berger MD, an experienced doctor, war veteran, and infectious disease specialist, “Those that get vaccinated and then catch an infection, like the Delta variant, may have not yet formed antibodies.” Dr. Berger further stated, “People should still take the usual precautions and wear masks, sanitize their hands, and practice social distancing to help limit the spread of the virus.”

It’s like sending soldiers into battle. The process involves intense preparation and strategy beforehand. However, even the most experienced veteran returning to the call of duty requires armor, like helmets and bulletproof vests, and is trained to follow standard safety measures. The reason for this is because war brings a great deal of uncertainty and high mortality risk. Wearing safety gear during on-ground combat will not prevent all adverse events. The gear is designed to prioritize and protect a soldier’s brain, heart, spine, and other vital organs from damage. The vaccines are meant to work the same way.

The Delta variant may be dashing the world’s hope of reaching herd immunity since vaccinated individuals can spread the virus as much as the uninfected.

This insight makes it more urgent for each individual to get vaccinated and not count on herd immunity or immunity from prior infections to protect them. Professor Sir Andrew Pollard of the Oxford Vaccine Group recently informed that COVID is not like measles where if 95% of the population is vaccinated, the rest are protected. He stated, “…anyone still uninfected at some point will meet the virus.”

Meanwhile, the death knell from COVID-19 and the Delta variant continues to sound.

As of August 10th, 2021, more than 4.3 Million COVID-19-related deaths have been reported to the World Health Organization (WHO). The United States is in the lead with 600,000, followed by 563,000 in Brazil, and over 428,000 in India. In the United States, with only 50% of the population vaccinated, the daily case count now stands at 100,000 and is expected to grow. According to the CDC, the Delta variant is now the cause of 83% of all new cases in the U.S.

While the U.K. reported the highest single-day deaths from COVID-19 on August 11th, 2021 (their highest since March as a result of cases from July), hospitalizations, ICU admissions, and deaths were much lower in this wave than at the beginning of the year. Over 75% of adults in Britain have been fully vaccinated, and 89% have received at least one dose.

In the United States, while the COVID-19 vaccines are under evaluation for safety and efficacy, several have been approved for emergency use.

Portland, OR, USA - Mar 2, 2021: A woman browses the FDA website to learn more about COVID-19 vaccines. FDA has issued emergency use authorization for Janssen vaccine, the third COVID-19 vaccine.


Are Vaccines Approved Under EUA or Emergency Use Authorization Safe?

Several countries have granted preliminary approvals for vaccines in light of the devastation caused by COVID-19 and its variants. In the United States, vaccines by Pfizer-BioNTech, Moderna, and Johnson & Johnson (J&J) received EUA approval. Seeing that it is the first time vaccines are being granted EUAs, how effective are the vaccines?

In an ideal world, there would be long-term data and lots of time to analyze and decide whether to get vaccinated. In the future, COVID-19 vaccines like the chickenpox and flu vaccine, are available for those who need it but are “not necessary”. But right now, like medics on a battlefield, the biggest concern is to stop the bleeding. In the case of COVID-19 and its variants, it means minimizing hospitalizations due to severe illness and deaths. The three vaccines authorized under EUA in the U.S have proven effective against moderate to severe symptomatic disease.

While the EUA is a temporary fast-tracking of potentially life-saving drugs or therapy, it is not granted without reviewing detailed submissions from vaccine manufacturers containing proof of safety and data from clinical trials on more than thousands of willing participants. Another reason for the rapid FDA review and response is that the COVID-19 pandemic is the highest priority. So, resources to evaluate COVID-19 vaccines have been diverted accordingly.

In short, natural immunity will not last forever, the Delta variant is much more capable of breaking through natural immunity, and unvaccinated COVID-19 survivors have a higher likelihood of getting reinfected. If you choose to get vaccinated, here is a comparison of the reported COVID-19 vaccine efficacy against the Delta variant.


Comparison of COVID-19 Vaccine Protection Against the Delta Variant

1.    Moderna:

The Moderna vaccine is a two-dose vaccine, taken 28 days apart. It is an mRNA vaccine that makes the spike protein and teaches our body to create antibodies.

Effectiveness against Delta variant:

  • Two doses: 94-95% effective against the Delta variant [1] [2].
  • Single-dose: 72% effective.

2.   Pfizer-BioNTech

The Pfizer-BioNTech vaccine is a two-dose vaccine taken 21 days apart. It is also an mRNA vaccine that makes the spike protein.

Effectiveness against Delta variant:

Reports vary between 79 – 95% so let us break them down:

  • A UK study demonstrates 88% overall effectiveness and 96% against hospitalization[3].
  • A Scotland study reported 79% effectiveness [4].
  • A study out of Canada showed 87% effectiveness [1].
  • A study out of Israel showed 90% effectiveness initially but more recently reported 41% effectiveness against symptomatic infections, but 91% effective against severe disease and 88% against hospitalization [5]. A report by the Ministry of Health, Israel, studying confirmed COVID-19 cases from January-July 2021, also showed that vaccinated individuals with pre-existing conditions are better protected against serious illness compared to non-vaccinated individuals without any risk factors [6].
  • A study from France reported 94% overall effectiveness with two doses [7].
  • A New York study stated 94-95% overall effectiveness [2].

3.   Johnson & Johnson – Janssen

The J&J Janssen vaccine is a viral vector vaccine, which uses inactivated and modified Adenovirus as a ‘Trojan horse’ to deliver the gene that encodes the SARS-CoV-2 spike protein. A well-known Bacillus Calmette Guerin (BCG) vaccine works the same way. The vaccine differs from other vaccines on the market in that it requires only one dose.

Effectiveness against Delta variant:

  • 9% efficacy in preventing moderate to severe disease. However, the study is small, and some experts now believe a booster may be required [2].

4.   AstraZeneca-Oxford (No EUA in the United States)

The AstraZeneca-Oxford vaccine, similar to the J&J Janssen vaccine, also works as a ‘Trojan Horse’ carrying valuable information to help train our immune system. The AstraZeneca vaccine requires two doses, taken 30 days apart.

Effectiveness against Delta variant:

  • The Public Health England study reported 79% overall effectiveness and 96% effective against severe disease[3].


Immunity to COVID Can be Tricky

All around the world, we are waging war against the COVID-19 virus and its variants. The Delta variant is the most dangerous and highly contagious of all emerging variants. Compared to the original COVID-19 and all its other variants, infection due to the Delta is most likely to result in death and severe illness.

Natural immunity gathered from a previous COVID-19 infection is not reliable protection from the Delta. Unvaccinated COVID-19 survivors have double the risk of being reinfected versus vaccinated COVID-19 survivors.

The bottom line is that regardless of the brand or type of vaccine you choose, experts recommend that you get fully vaccinated to protect yourself and your loved ones – even if you had COVID-19 in the past.


[1]S. N. e. al., “Effectiveness of COVID-19 vaccines against variants of concern, Canada,” Pre-Print, 2021.
[2]T. T. e. al., “Comparison of Neutralizing Antibody Titers Elicited by mRNA and Adenoviral Vector Vaccine against SARS-CoV-2 Variants,” July 19th 2021. [Online][Accessed August 11th 2021].
[3]Public Health England, “GOV. U.K.,” June 14th 2021. [Online][Accessed 11 August 2021].
[4]Sheikh, Aziz; McMenamin, Jim; Taylor, Bob; Robertson, Chris; Public Health Scotland and EAVE II Collaborators, “SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness,” The Lancet, pp. 2461-2462, June 14th 2021.
[5]Ministry of Health, Israel, “GOV. I.L.,” July 22nd 2021. [Online][Accessed 11 August 2021].
[6]Ministry of Health, Israel, “Comparative Review of Confirmed Cases Data from January 2021 and July 2021,”
[7]D. Planas, D. Veyer, O. Schwartz and e. al., “Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization,” Nature, vol. 596, p. 276–280, 2021.


Chandana Balasubramanian

Chandana Balasubramanian is an experienced healthcare executive who writes on the intersection of healthcare and technology. She is the President of Global Insight Advisory Network, and has a Masters degree in Biomedical Engineering from the University of Wisconsin-Madison, USA.

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