Why are some people testing positive more than once?

Dr Maria Van Kerkhove of the World Health Organisation (WHO) says some people are testing positive more than once for coronavirus - but it doesn't mean they have been reinfected.

Speaking on The Andrew Marr Show, she said doctors were finding instances where "dead cells" that emerged during the healing process of the lungs were testing positive for Covid-19, but the individuals themselves were not reinfected.

View here (BBC, May 3, 2020)

Three potential futures for Covid-19: recurring small outbreaks, a monster wave, or a persistent crisis

‘What all three scenarios agree on is this: There is virtually no chance Covid-19 will end when the world bids good riddance to a calamitous 2020. The reason is the same as why the disease has taken such a toll its first time through: No one had immunity to the new coronavirus.

“This pandemic is not going to settle down until there is sufficient population immunity,” slightly above 50%, epidemiologist Gabriel Leung of the University of Hong Kong told a New York Academy of Sciences briefing.

‘Since the world “is far from that level of immunity,” said Osterholm (he estimates that no more than 5% of the world population is immune to the new coronavirus as a result of surviving their infection), “this virus is going to keep finding people. It’s going to keep spreading through the population.” And that, he said, “means we’re in for a long haul”.’

Read here (STAT News, May 1, 2020)

Tests in recovered patients found false positives, not reinfections, experts say

‘South Korea’s infectious disease experts said Thursday that dead virus fragments were the likely cause of over 260 people here testing positive again for the novel coronavirus days and even weeks after marking full recoveries.

‘Oh Myoung-don, who leads the central clinical committee for emerging disease control, said the committee members found little reason to believe that those cases could be COVID-19 reinfections or reactivations, which would have made global efforts to contain the virus much more daunting. “The tests detected the ribonucleic acid of the dead virus,” said Oh, a Seoul National University hospital doctor, at a press conference Thursday held at the National Medical Center.’

Read here (The Korea Herald, April 29, 2020)

Immunity passports 'could increase virus spread': WHO

‘Governments should not issue so-called "immunity passports" or "risk-free certificates" as a way of easing lockdowns, the World Health Organization (WHO) says... It said there was "no evidence" that people who had developed antibodies after recovering from the virus were protected against a second infection... Such a move could actually increase virus transmission, it warned... People who assumed they were immune might stop taking precautions, it said.'

Read here (BBC, April 25, 2020)

WHO and ”immunity passports”: No clear evidence people who have recovered cannot be reinfected

‘Some governments have suggested that the detection of antibodies to the SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for an “immunity passport” or “risk-free certificate” that would enable individuals to travel or to return to work assuming that they are protected against re-infection. There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.’

Read here (WHO, April 24, 2020)

Lockdown, vaccine, herd immunity. Can there be a winning exit strategy?

‘Lockdowns buy precious time but are not a strategy. The immediate fire is extinguished but the population remains vulnerable as large numbers lack any immunity to Covid-19 – akin to a forest-full of combustible material. It will only take a spark. Exit strategies for Covid-19 must consider this longer perspective, but the following charts explain why there will be no easy solutions and many ethical dilemmas lie ahead.’

NOTE: Dr Yap Wei Aun is a health systems specialist and adviser to the former Malaysian Minister of Health

Read here (South China Morning Post, April 24, 2020)

Developing a National Strategy for Serology (antibody testing) in the United States: Publication by John Hopkins

‘Serology tests will be an important tool for public health workers to estimate the prevalence of disease. These tests will be in high demand by individuals who hope to assess their risks of immunity to SARS-CoV-2. Serology testing, among other nonpharmaceutical interventions, can help to bridge the time before a vaccine is available. However, validated, accurate tests are currently in short supply. In this report, we seek to draw attention to the options for expanding access so that the potential benefits of serology tests can be realised as soon as practicable.’

Download here (John Hopkins Center for Health and Security, April 22, 2020)

Everything we know about coronavirus immunity and antibodies — and plenty we still don’t

‘But as the tests roll out, some experts are trying to inject a bit of restraint into the excitement that the results of these tests could, for example, clear people to get back to work. Some antibody tests have not been validated, they warn. Even those that have been can still provide false results. And an accurate positive test may be hard to interpret: the virus is so new that researchers cannot say for sure what sort of results will signal immunity or how long that armor will last.

‘They caution that policymakers may be making sweeping economic and social decisions — plans to reopen businesses or schools, for example — based on limited data, assumptions, and what’s known about other viruses. President Trump last week unveiled a three-phased approach to reopen the country; he said some states that have seen declining case counts could start easing social distancing requirements immediately. And some authorities have raised the idea of granting “immunity passports” to people who recover from the virus to allow them to return to daily life without restrictions.’

Read here (STAT News, April 20, 2020)

How Covid-19 immunity compares to other diseases

If you get Covid-19 and recover does that mean you are immune to the virus? If you become immune, how long does that immunity last? We are still looking for answers to many of these questions. In the meantime, Dr. Seema Yasmin takes a look at the human body's immunity to some other viral infections such as chickenpox, HIV and the common cold.

View here (Wired, 9-minute video, April 17, 2020)

Malaysia already has a contact tracing app (Gerak Malaysia) and it’s downloadable now

‘The Malaysian Communications and Multimedia Commission is testing a beta app called Gerak Malaysia that can do just that and it uses location tracking...

‘At hospitals, the QR code can be used to determine your risk level and it will allow frontliners to assign you to the right queue. For example, if you’ve been to an area that was visited by a confirmed Covid-19 case, you will be flagged as a high-risk...

‘The QR code can also assist the police and armed forces at the roadblocks as they can determine whether you’re travelling within the permitted radius. This feature can potentially replace the approval letters that are required to be presented to the police. As a result, this feature can help speed up the checks and reduce congestion...’

Read here (The Malay Mail, April 17, 2020)

The mechanics of mobile contact tracing: Information collected can be quite extensive

‘A mobile phone App can make contact tracing and notification instantaneous upon case confirmation. By keeping a temporary record of proximity events between individuals, it can immediately alert recent close contacts of diagnosed cases and prompt them to self-isolate.

‘Apps with similar aims have been deployed in China. Public health policy was implemented using an App which was not compulsory but was required to move between quarters and into public spaces and public transport. The App allows a central database to collect data on user movement and coronavirus diagnosis and displays a green, amber or red code to relax or enforce restrictions on movement. The database is reported to be analysed by an artificial intelligence algorithm that issues the colour codes. The App is a plug-in for the WeChat and Alipay Apps and has been generally adopted...’

Read here (Science, March 30, 2020)