We recently conducted a study to find out key information about immunity and antibodies in response to COVID-19.

As the only not-for-profit offering COVID-19 antibody testing at cost, we want to contribute to getting our communities back on track. By conducting this research and sharing our results, we believe it can help to advance our understanding of the virus and immunity to it.

We would like to thank everyone who took the time to complete our survey. Your support is invaluable and has helped us to gain these key insights, which is immensely helpful in our ongoing research.

What did we want to achieve?

We wanted to gain a better understanding of antibody duration and reinfection from our community’s perspective.

One of the key things that motivated this study was the opportunity to obtain insights from a wider set of individuals, as opposed to studies conducted to date which have focused on healthcare workers or the critically ill. As such, we strongly believe that our customer base of +20,000 individuals is extremely representative of the impact of COVID-19 across the UK.

Who were our respondents?

We had 5,349 respondents, 57% were female and 43% male. Of these, 27% tested positive for antibodies whilst 73% tested negative.

What insights were we looking for?

• Antibody duration
• Reinfection and immunity
• Impact of severity of symptoms
• Percentage believed to be suffering from “long-covid”

What did our key findings reveal?

Impact of severity of symptoms

• Amongst our respondents, the majority experienced moderate symptoms (some effect on daily life)
• Amongst all of our respondents, 10% have experienced symptoms of Long Covid
• For our respondents who have tested positive for antibodies, 12% have experienced symptoms of Long Covid

Reinfection and immunity

• Our data shows that for people with COVID-19 antibodies, reinfection only occurred in less than 0.5%

For comparison, the Siren study conducted by Public Health England detected 44 potential reinfections out of 20,787 participants.

The study was conducted between 18 June and 9 November and tested healthcare workers to gain a better understanding of rates of reinfection. Results from the research found that 83% of the participants had protection from reinfection that appeared to last for five months from first becoming unwell.

This research combined with our own gives us strong optimism that antibodies provide a degree of protection from reinfection. However, early evidence from the next stage of the Siren study suggested that some people who are protected by antibodies still carry high levels of the virus and could continue to infect others, which highlights the importance of continuing to follow the social distancing guidelines to protect one another.

Antibody duration

• Based on the symptom onset date, patients test positive for antibodies up to nine months after infection
• Our data indicates a gradual build up of antibodies through time as well as a strong correlation between symptom severity and antibody response, with asymptomatic patients less likely to test positive for antibodies

From looking at the data, we found that the longest duration for antibody analysis are those who were exposed to COVID-19 in March/April 2020. There was limited testing available at the time, especially for mild cases outside of hospital or healthcare, which may have motivated individuals to take antibody tests in order to explain previous symptoms.

Kelly Klifa, Co-Founder of TFA, said: “Our data clearly shows that COVID-19 antibodies can remain in the system over time and prevent individuals from becoming reinfected. This is great news for the vaccine programme, as it’s based on the same premise – providing protection against the virus by encouraging the body to produce COVID-19 antibodies.

“However, the data also shows that not everybody who’s had the virus retains antibodies in their system, and they may still be vulnerable to reinfection. We encourage everybody to get vaccinated as soon as the opportunity arises, but in the meantime, we’re offering a way for people to understand whether they have antibodies, and if so, at what level.”

What’s next for Immunity Research?

Further research and advancements in diagnostics are vital in pinpointing the correlation between antibody levels and protection.

We recently launched our COVID-19 Immunity Tracker, which provides a quantitative view of protective IgG antibodies directed against the spike protein of SARS-CoV-2. The test can be used to monitor immune responses to natural infection and vaccination.

Another aspect of this test is that it can be used to compare results across other test manufacturers and in line with the World Health Organisation standards, helping us understand our immunity level even further.

James Monico, Co-Founder of TFA, said: “Vaccination is the way out of this crisis, but it also requires the close monitoring of immunity at an individual level through antibody testing. We need to better understand the connection between antibody levels and the extent of immunity – what is the cut-off point where individuals start to be at risk of infection again? It’s also important to bear in mind that as variants emerge, and with immunity probably decreasing over time, there is no vaccine that currently provides a single silver bullet.

“By providing this test at an affordable price to everyone, we hope to contribute to a wider understanding of the rules of COVID-19 immunity.”

Missed our webinar?

For further understanding of our results, you can watch a recording of our recent webinar, COVID-19 Immunity: Findings from the Testing For All Study here.

Please use this passcode to access the recording: jq?4Xnxr

During the webinar, Kelly & James, TFA Co-Founders, together along with Dr Renée Hoenderkamp, our Clinical Advisor and resident GP for the BBC Radio London, discuss topics from our research and answer questions from the audience.

You can buy our new COVID-19 Immunity Tracker test here.