How long does it take to recover, how do you know you’ve recovered and can you catch Covid-19 twice?
If you’ve had Covid-19 when are you officially recovered? Turns out there’s no test in New Zealand. It’s judged by time of onset and last symptoms.
How do I tick the statistical box of ‘recovered’?
If it’s been at least 10 days since you first had symptoms, and you’ve been symptom-free for 48 hours, the Ministry of Health considers you have recovered from Covid-19. This means the shortest possible time in self-isolation would be 10 days.
However, even when these criteria are met, only the health professional responsible for your daily monitoring can approve an end to self-isolation.
If you’re a “super-shedder” and have infected a lot of people, or if you have underlying health conditions, or an occupation which may cause the health professional concern, there’s a chance you may have to stay in self-isolation for longer.
How is this number of days decided?
When asked in Thursday’s press conference, Director-General of Health Ashley Bloomfield’s response was: “That’s based in international practice.”
Because this is a new disease, scientists have been feeling their way in the dark.
One study out of Germany, yet to be peer-reviewed, shows infectiousness is higher at the beginning of showing symptoms. After around 10 days after falling ill, infectiousness reduces significantly to a point where there is hardly any virus present.
Another study from Chinese patients found the virus was still detectable for up to 20 days after symptoms began, although the level of the virus dropped over time.
In the United States, the Centres for Disease Control and Prevention (CDC) sets the minimum number of days at seven. If at least seven days have passed since the first symptoms began and the patient has had no fever for three days, they are considered recovered.
However, unlike New Zealand, there’s an option to get tested. If you have two negative tests 24 hours apart, no fever and symptoms such as coughing have improved, then your doctor can give you an all clear to leave self-isolation.
The CDC’s guidance comes with cautionary footnotes pointing out it’s based on “limited information”.
“This recommendation will prevent most, but may not prevent all instances of secondary spread. The risk of transmission after recovery is likely very substantially less than that during illness.”
A Ministry of Health spokesperson said the Technical Advisory Group meeting today will discuss the issue again.
“This is the current criteria being used in New Zealand which is largely in line with the approach in Australia – though they require 72 hours of being symptom-free.”
Once I’ve had Covid-19 will I be immune?
Probably is the short answer. The longer answer is it’s not know how long immunity lasts.
University of Auckland vaccinologist Associate Professor Helen Petousis-Harris said there’s good data this happens, but there have also been exceptions. One woman in Japan is said to have tested positive for Covid-19 twice.
“The general thinking is that protection for at least a few years is likely, based on what we know about other coronaviruses. With the common human coronaviruses that cause colds we know that people make immune responses and have antibodies, but after a few years they can get reinfected.”
Could previously infected people return to work as they’re no longer at risk?
There’s been talk in some countries of the idea of an immunity passport. This could be issued to people who have undergone a serology test which requires just a pin prick of blood.
“The UK government has reportedly placed an order for 3.5 million serology test kits and intends to offer the test to frontline doctors and nurses, allowing them to see if they have already been exposed to the virus and are therefore immune,” said University of Auckland senior virology lecturer Dr John Taylor.
“Some caution needs to be exercised here though: it may take some time to confirm that a positive serology test indicates complete protection against reinfection.”
Some have expressed concern an immunity passport approach might encourage people experiencing financial difficulty to contract the virus on purpose in the hope of being able return to work sooner.
How did New Zealand have so many recovered when we started out with so few cases?
This has been a question Newsroom has received a number of times. It all comes down to what stage of the illness a person was at when the test result was confirmed.
Not all people will have been tested on the first day they had symptoms. They may have been ill for two or three days prior to getting a test. There’s also a 24 to 48 hour delay in getting test results