People that had SARS-CoV-2 infections may think that they have “natural immunity” and are protected from getting re-infected from this COVID-19 virus. But there are 2 new studies showing evidence that vaccination generates a more vigorous B and T cell (immune memory cells) response than does natural infection. It shows that vaccination is particularly stronger in people with previous SARS-CoV-2 infections.

Researchers evaluated people who were vaccinated with the mRNA vaccine after natural infection and people who were vaccinated but had no prior infection. Memory B cells against SARS CoV-2 were 5-10-fold higher when vaccination followed natural infection than after natural infection or vaccination alone. The most surprising result was that in people who were vaccinated after natural infections, neutralizing antibodies against the beta variant were higher. They were 25 times higher than after vaccines alone and 100 times higher than after natural infection alone. This was amazing since natural infections were almost never with the beta variant and that vaccines don’t target the beta variant spike protein.

Other studies as well have shown similar results. A study in the CDC (Centers for Disease Control and Prevention) Morbidity and Mortality Weekly report shows 2.3 times the number of reinfections with natural immunity compared to breakthrough infections in those who are vaccinated. It is unclear how effective natural infection is against other variants, particularly the Delta variant. This new variant, as well as the lambda variant, may weaken the protection provided by having been previously infected by SARS-CoV-2.

People who have had COVID-19 are advised to be vaccinated. It will very likely offer better protection against symptomatic reinfections, even with the Delta and future variants.

References: Diamond, F. Kavanagh, K. Get vaccinated even if you’ve gotten COVID-19, study suggests. Infection Control Today 2021, Aug 8.

Stamatatos, L et al. mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection. Science 2021 Mar 25; 372: 1413.

Deepti Gurdasani is a British-Indian epidemiologist who is a public researcher at the Queen Mary University of London. This is a part of a thread in which she discusses Long COVID and the implications in the community.

Several studies have put the overall incidence of long COVID between 10-50% of those infected. Scientific consensus is that Long COVID is not just a respiratory disease but a “real” multi-system syndrome that occurs in those infected- predominantly impacting the young. The Office of National Statistics (ONS) data and REACT-1 data compares symptoms post infection among those infected with control groups of those confirmed not to have infection. These are some of the most robust data on Long COVID based on PCR tests through random nationally representative surveys of thousands of people (ONS data 313, 216, and REACT-1 data 508,707 samples).

Here are some highlights:

Most people present with a combination of symptoms and of the 1 million people affected, 2/3rds said it impacted their day-to-day activity. About 400,000 have had persistent symptoms for over 1 year. Sadly this included 9000 children who have been affected for more than a year. Those with the highest risk factors were women, increasing age, smoking, and low income.  There is strong evidence that even those with mild symptoms can have long-term structural brain changes including thinning of grey matter in brain areas related to smell, taste, memory and emotion. The risk of organ dysfunction was 38.9% in those aged 19-49 years. This clearly impacts a large proportion of young people.

So to summarize, long COVID is common- even in young children with mild infection. It usually includes multiple symptoms, that in many, affects day-to-day lives. Remember that children under the age of 12 cannot get vaccinated. Let’s do our part and get fully vaccinated for ourselves, our families (and children) and our community.

Follow the full thread at @dgurdasani1. Other links are Post Acute COVID-19 Syndrome and Survivor Corps

Electronic health records were studied at multiple institutions in the U.K. Researchers estimated the incidence of neurological or psychiatric sequela in 236,000 people with COVID-19 infection. During the 6 month follow-up, 13% were diagnosed for the first time with either a neurological or psychiatric condition with no prior history of these conditions. Another 21% of patients who had prior conditions developed new conditions.

These rates were compared with rates in 342,000 people with influenza and other respiratory tract infections. The incidence of neurological and psychiatric diagnoses were significantly higher in COVID- 19 patients. The most common diagnoses were anxiety (17.4%), psychotic disorder (2.8%), ischemic stroke (2.1%), dementia (0.7%) and intracranial hemorrhage (0.6%).

The most concerning were those whose acute COVID-19 infection caused encephalopathy (defined as delirium or other altered mental states). In those with encephalopathy, the chances of developing mood disorder were 22%, anxiety disorder 22%, ischemic stroke 9%, psychosis 7% and dementia 5%.

This large study demonstrates that various psychiatric and neurological conditions develop with a relatively high incidence in 6 months following acute COVID-19 infection in people with or without previous disorders. We need to look for interventions to address these sequela for post COVID patients. It is not just about surviving this infection, but hoping that you don’t fall into the long-hauler conditions that are so debilitating. One site connecting people with these symptoms that provides support and resources is survivor corps.

It is unknown whether the post COVID mood and anxiety disorders are due to the psychological stress of the illness, or that they are triggered by neuro-inflammation caused by the infection. Regardless of whether it’s the “chicken or the egg”, these symptoms are real and thus far unpredictable as to how long they may last.

Reference: Taquet M et al. Six month neurological and psychiatric outcomes in 236379 survivors of COVID-19; A retrospective cohort study using electronic health records. Lancet Psychiatry 2021 April 8:416.

The question that remains on people’s minds is how effective and long lasting the immunity is from either having had the COVID-19 infection or the vaccine. Now we are starting to get some answers. According to a population-wide study in Australia using data from the SARS-CoV-2 national infection reporting system, the re-infection rate has been low.

Researchers compared the odds of SARS-CoV-2 re-infections of COVID-19 survivors of the first wave (February- April 30, 2020) versus the odds of first infections in the remainder general population (by tracking PCR confirmed infections of both groups) during the second wave (September 1st-November 30, 2020). Out of the almost 15,000 COVID-19 survivors of the first wave and 253,000 infections in the 8.9 million individuals of the remaining general population, only 40 tentative re-infections were recorded.

This shows a relatively low re-infection rate of SARS-CoV-2 in Australia. Assuming that convalescents were exposed to COVID-19 at the same rate as people in the general population during the second wave, reduction in risk for re-infection was >90% which lasted for at least 7 months. Protection against SARS-CoV-2 after natural infection is comparable with the highest estimates on vaccine efficacies. Based on this data, there appears to be considerable protective immunity for at least 7 months after COVID-19 infection and no urgent need for booster vaccinations in COVID-19 convalescents. More well-designed research is needed for improving evidence-based public health decisions and vaccination strategies.

Reference: Pilz S et al. SARS-CoV-2 re-infection risk in Australia. Eur J Clin Invest 2021 April; 51:e13520.