How long does it take to be certain that you’ve been infected with Covid-19? And if indeed infected, how long would it take for you to be free of the novel coronavirus? These are tough questions to answer conclusively, but here’s what the first 100 fully recovered cases in Singapore can tell us.

Several excellent dashboards have been created to track the progress of the Covid-19 outbreak in Singapore (click [[[here](https://www.straitstimes.com/multimedia/graphics/2020/02/spore-virus-cases/index.html?shell)](https://infographics.channelnewsasia.com/covid-19/coronavirus-singapore-clusters.html?cid=covid19_desktop-banner_19022020_cna)](https://experience.arcgis.com/experience/7e30edc490a5441a874f9efe67bd8b89), here, here, and here), and it would be pointless to try to duplicate what these better resourced teams have done.
In this post I’ll focus instead on exploring two questions on everyone’s mind:
- Q1: If I test positive for Covid-19, how long would a full recovery take?
There’s no global standard at this point, and affected countries have adopted different guidelines as to when a Covid-19 patient is cleared to be discharged from a hospital.
In the Singapore context, Covid-19 patients are deemed to have fully recovered only after they successfully test negative for two swab tests at least 24 hours apart. Only then can they be discharged from the hospitals. This is done to ensure that the patients don’t go on to infect others when they return to the community.
In other words, recovery from Covid-19 symptoms alone is not considered a full recovery and would not qualify you for discharge from hospitals in Singapore.
So far, patients among the first 100 fully recovered Covid-19 cases in the city-state have taken between one and 31 days to be discharged, if we start counting from the day their infection was officially confirmed. The median number of days in this confirmation-discharge window is 11 days.
- Q2: If I have symptoms, how long do I have to wait to be certain that it is Covid-19?
This is the tougher of the two questions to answer due to gaps in our knowledge of Covid-19, and complex cases with either no symptoms or buck the norm for the 14-day incubation period. In Singapore, the vast majority of patients among the first 100 fully recovered cases were confirmed within 14 days of the reported onset of symptoms like fever, sore throat and difficulties in breathing.
But eight patients had no symptoms and eight cases took 15 days or more before they were confirmed. There is no conclusive explanation so far for these unusual cases, as well as similar ones that have been reported around the world.
This is not a medical study, obviously, and I’m not an epidemiologist. But I have taken extra care to use labels/definitions that are clear, unambiguous and non-alarmist.
My goal here is to try to present the underlying trends in the public data in a manner that is clear and easy to understand, while being upfront with the limits of the dataset and my lack of domain expertise.
Singapore has won praise for its early handling of the Covid-19 outbreak, but signs are that this early success inadvertently bred complacency among some residents. At a time when the outbreak has gone global, this sense of complacency would prove costly given Singapore’s high population density.
From my past experience as a journalist, most people tune out when you try to engage them on "big picture" explanations. But they may pay a little bit more attention if the impact on their personal wellbeing is spelt out more clearly.
This is what I hope to achieve with this post.
1. DATA, DEFINITIONS AND CAVEATS
Before we get to the charts, it is important to first understand the limits of the public dataset and avoid jumping to hasty conclusions. The information released by the Singapore authorities, while detailed, is mostly aimed at keeping the public informed on a daily basis. The dataset does not contain detailed medical information about the patients that would inform a full-fledged study.
As such, I’m steering clear of labels like "incubation period" and "recovery period", which have specific meanings in medical research and are best left to the experts.
1.1 DATA SOURCE
I assembled the dataset for the first 100 fully recovered cases manually from daily press releases issued by Singapore’s Health Ministry. You can download a copy of the dataset here, or via the Github repo for this post.

For the record, the first 100 full recovered patients in Singapore are: Cases 01–34, 36–40, 43–81, 83–89, 91–93, 95–96, 98, 102, 106–107, 110–112, 138, 148, and 151.
The first patient to make a full recovery in Singapore is Case 07, a 35-year-old mainland Chinese national who was discharged on February 04, eight days after he was confirmed to be Covid-19 positive on January 27 2020.
The 100th discharged patient added to the sample is Case 102, a 41-year-old Filipino woman who was discharged on March 14 2020. Eight unrelated patients, including Case 102, were discharged on March 14, according to the Singapore health ministry. Recovered patients 103, 135, 146, 150 and 160 were not added to this dataset.
I picked the first 100 recovered cases for practical reasons. Clearly, the overall number of Covid-19 cases in Singapore is still growing, and the trends will change alongside the numbers. So bear in mind that this is an initial exploration. I’ll update or write a new post when appropriate.
Minor note to non-Singaporean readers: Dates in the CSV file were recorded in the day/month/year format per the norm in Singapore.
1.2 DEFINITIONS
The two definitions used in this post are unfortunately clunky, but I opted to be as unambiguous as possible so that we are focused on what the limited public data actually says, instead of going down the slippery road of over-interpreting what we think the data is saying.
Case in point: The public data does not contain information about when patients were first exposed to the virus, or their daily condition while in the hospitals. The Singapore authorities also do not disclose how long a patient took to recover from symptoms at the hospital, versus the time he or she spent waiting for results of the swab tests.
So it would be highly problematic to adopt phrases like "incubation period" and "recovery period" in this post, as they have specific medical definitions which the public data in Singapore does not necessarily address.
DEFINITION #1: Confirmation-Discharge Window
In this post, I’ll use the term "confirmation-discharge window" as a shorthand for the number of days between a patient’s Covid-19 infection confirmation date, and his/her official discharge date, as announced by the Singapore health ministry. These dates are matters of public record and are not in dispute.

Starting the clock from the confirmation date gives us a consistent baseline for comparisons in a fast-moving environment. In the early days of the outbreak, you would expect a noticeable gap between a patient’s hospital admission and results of a Covid-19 test. But as newer test kits emerge, this wait time would be shortened dramatically.
DEFINITION #2: Symptoms-Confirmation Window
The pre-confirmation phase is tricky territory given the global disparity in access to medical facilities and Covid-19 test kits. In Singapore, the health ministry also releases a number of key dates for each Covid-19 case, including the dates of arrival in Singapore (for imported cases), and dates for self-initiated visits to a clinic or hospital (if applicable).
The period of uncertainty between exposure to Covid-19 and official confirmation of infection can thus be defined in many ways, depending on how one combines the available dates.
To avoid over-complicating matters, I’ll use a straightforward definition of the pre-confirmation phase as the "symptoms-confirmation window", ie, the number of days between the reported onset of symptoms and official confirmation of Covid-19 infection.

To be sure, there are some doubts about the veracity of the dates of onset of symptoms reported by the patients, particularly in times of stress and social stigma. But that’s the most reliable "start date" that is consistently available in the Singapore data. I opted not to use the dates involving hospital admissions and self-initiated visits to the clinics as the diagnosis on these occasions have not been disclosed.
2. DEMOGRAPHIC BREAKDOWN OF SINGAPORE’S FIRST 100 FULLY RECOVERED PATIENTS
I don’t intend to duplicate the excellent Covid-19 dashboards already out there. But some charts broken down along demographic lines would still be useful for the analysis in this post. For this, I created an interactive chart on Flourish that can get the job done quickly. You can access it here.
In this sample of 100, we have 23 imported cases and 77 cases of local transmission. Forty of the recovered patients are women, and the rest are men.


In terms of nationalities, we have eight groups, if we consider Singapore permanent residents separately. There are:
- 67 Singaporeans
- 19 mainland Chinese nationals
- 6 Singapore PRs
- 4 Bangladeshis
- 1 each of nationals from Indonesia, Japan, Malaysia and the Philippines

Age-wise, the bulk of the first 100 fully recovered patients – 75 – are aged between 30 to 59 years old. The single age range that has the most number of Covid-19 patients is the 30–39 segment, with 28 people (18 men and 10 women).

3. IF YOU’VE TESTED POSITIVE FOR COVID-19, HOW LONG WOULD A FULL RECOVERY TAKE?
In a rare televised address on March 12, Singapore Prime Minister Lee Hsien Loong said 80% of Covid-19 patients in Singapore "only experience mild symptoms". He did not explain what he meant specifically by "mild".
But if you have been infected with Covid-19, recovering from the symptoms is just one part of the ordeal.
Most patients among Singapore’s first 100 fully recovered cases, both young and old, required a lengthy hospital stay because of the additional time needed to ensure that they have stopped transmitting the highly contagious Covid-19 virus.
Average number of days between hospital discharge and Covid-19 confirmation: 12.29
Median number of days between hospital discharge and Covid-19 confirmation: 11.0
Minimum number of days between hospital discharge and Covid-19 confirmation: 1
Maximum number of days between hospital discharge and Covid-19 confirmation: 31
This is an important distinction to make, as the mistaken belief that Covid-19 is "just a bad flu" (it is not) that you can quickly recover from is at the heart of the sense of complacency among many in Singapore and elsewhere.
Data from the first 100 recovered cases in Singapore show that the median number of days for the confirmation-discharge window is 11 days. A third (33) of the patients took 15 days or more to be discharged, from the time of the confirmation of infection. Only eight patients were discharged within three days or less of confirmation of infection.

The chart above also shows why health authorities are concerned about a major spike in the number of new Covid-19 cases. If there’s an explosive surge in new infections, the huge amount of time and resources needed to make sure large numbers of patients are safe to return to the community could overwhelm a country’s medical system.
Put simply, this is not just about your personal ability to recover from Covid-19 infection. The concerns are wider and systemic in nature, that is, over the healthcare system’s ability to deal with a sudden surge in patients who could be infectious for weeks.
3.1 CONFIRMATION-DISCHARGE WINDOW: A GANTT CHART VISUALISATION
Gantt charts are typically used to illustrate project schedules. But in this case, it works pretty well in showing each patient’s confirmation-discharge window. You can download a copy of the interactive chart here (it’s an html file; Medium doesn’t allow a direct embed for interactive charts). Simply hover over each bar to see the meta-data for a particular case, and the number of days he/she took between confirmation and full recovery.

The Gantt chart is useful for an overview, and allows you to quickly pick out the unusual cases:
3.1.1 WHICH CASES TOOK THE LEAST AMOUNT OF TIME FOR A FULL RECOVERY?
Case 151, which officially registered just one day between official confirmation and discharge, the perhaps the most unusual of the lot.
The Singapore health ministry’s official press release seems to suggest that the 51-year-old Singaporean man recovered from Covid-19 on his own, after first reporting onset of symptoms on February 4. It took the results of a serological test on March 8 to confirm that he had an "earlier Covid-19 infection". He was discharged a day later on March 9.

Cases 76, 83 and 84 took just two days to be discharged after they were officially confirmed to be infected. Cases 83 and 84 are part of the Mei Hwan Drive cluster that is in turn linked to two other church clusters.
Patient 76 was among the Singaporeans evacuated from Wuhan, the epicenter of the outbreak, on February 9. He had shown no symptoms prior to boarding the flight, and was quarantined upon arrival in Singapore as part of the city-state’s containment measures. He tested positive for Covid-19 only on February 16.
It remains unclear why these cases took such a short time to stage a full recovery.
3.1.2 WHICH CASE TOOK THE LONGEST FOR A FULL RECOVERY?
Cases 53 holds the record so far, taking 31 days from the time of confirmation of infection to his eventual discharge from hospital. The 54-year-old Singaporean man was part of a Covid-19 cluster linked to a local church, the Grace Assembly of God. He first reported onset of symptoms on February 10, and was tested positive for Covid-19 two days later.

However, it is unclear what is the split between the days he took to recover from Covid-19 symptoms, and the time needed for him to clear the swab tests. The publicly available data in Singapore does not contain detailed information about a patient’s condition during Covid-19 treatment.
4. DO PATIENTS OF DIFFERENT GENDER AND AGE RECOVER AT A DIFFERENT PACE?
A study of 1,000 Covid-19 patients across China found that women were more likely to survive. Thankfully there has been no Covid-19 related fatality in Singapore just yet. But among the first 100 fully recovered patients in Singapore, do men and women recover fully at a different pace?
4.1 HOW THE CONFIRMATION-RECOVERY WINDOW DIFFERS FOR MEN AND WOMEN
There are 60 men and 40 women among Singapore’s first 100 fully recovered Covid-19 patients. But the boxplot below shows that both genders took the same median number of days for a full recovery – 11 days.
The small sample size could be a factor, and it will be interesting to see how things change when we have a larger number of fully recovered patients. If you are unfamiliar with boxplots, check out this explainer here.

4.2 HOW THE CONFIRMATION-RECOVERY WINDOW DIFFERS ACROSS AGE GROUPS
Most of us might assume that age would have a bearing on the time needed for full recovery, but data from the first 100 Covid-19 cases in Singapore threw up some surprises:

With the exception of those in the youngest age group of under 9, who have a median confirmation-discharge window of four days, we don’t see younger patients waging a full recovery significantly faster than the older ones.
The median number of days needed for full recovery in the age groups of 10–19, 20–29, and 40–49 are in fact longer than the overall median of 11 days for all 100 recovered patients.
This is surprising at first sight, but less so when you go back to the definition of a full recovery – which is that patients must prove that they’ve stopped transmitting the virus, and not merely recovered from the symptoms. In other words, the median time needed to be free of Covid-19 might not deviate all that much across age groups, even if younger patients recover faster from the symptoms. This needs verification by experts in a larger study, of course.
The data for those in the 60–69 age group is highly unusual. The median confirmation-discharge window for this age segment is five days, and there is an outlier, Case 01, that took 27 days (2.5 times overall median) between confirmation of infection and discharge. I’ll avoid over-interpreting this for the moment, given the small sample size in this initial exploration.
An interactive version of the boxplot is available here. Hover over the data points to see the detailed meta-data for each case, or over the boxes to see the inter-quartile distribution of the recovery period for patients in a particular age range.

5. HOW LONG DOES IT TAKE TO BE SURE WHETHER I HAVE BEEN INFECTED WITH COVID-19 OR NOT?
This is tricky territory given the global disparity in access to medical facilities and Covid-19 test kits. The official FAQ on the Singapore health ministry’s website says "the incubation period is up to 14 days", citing data from Covid-19 cases in China.
This gels with a breakdown of the data for the first 100 fully recovered cases in Singapore, where only eight patients took longer than 14 days from onset of symptoms to test positive for Covid-19:

Eight patients had no symptoms, and more than half of the 92 patients who had symptoms were confirmed as being Covid-19 positive within seven days or less. Overall, the median number of days between onset of symptoms and confirmation of infection is six days.
Average number of days between symptoms and confirmation: 7.434782608695652
Median number of days between symptoms and confirmation: 6.0
Minimum number of between symptoms and confirmation: 1.0
Maximum number of days between symptoms and confirmation: 33.0
5.1 GANTT CHART VISUALISATION OF SYMPTOMS-CONFIRMATION WINDOW
Repeating the use of a Gantt chart, we can again tell which are the cases which took an unusually long time for the infection to be confirmed. Cases 151, 91, and 83 immediately stand out as highly complex cases. You can download a copy of the interactive Plotly chart here.

Case 151, which we briefly discussed earlier, nominally had a 33-day gap between onset of symptoms and confirmation of infection. But the reality is far more complicated, as we have seen from the health ministry’s press release on March 9.
He began having symptoms on Feb 4, but it took a serological test on March 8 to confirm that he had an earlier Covid-19 infection. The authorities did not say when exactly he was infected, or if the serological test could discern the date of a prior infection. Case 151 was discharged a day later on March 9.
Case 151 is not the only outlier among patients who reported symptoms. Seven other patients – Cases 30, 66, 68, 83, 84, 89, and 91 – in our sample of 100 recovered cases took more than 14 days between onset of symptoms and confirmation of Covid-19. They are all cases of local transmission:

Case 91, who took 30 days between reported onset of symptoms and confirmation, first reported being unwell on January 23 and sought treatment at a clinic on three separate occasions – on February 1, 6 and 10, according to the health ministry’s press release dated February 25.
The ministry did not say what the diagnosis was for the 58-year-old woman on those occasions. She was referred to the National Centre for Infectious Diseases (NCID) on February 18 after she was identified as a contact of Case 66, the primary case of the Grace Assembly of God church cluster. Case 91 tested positive for Covid-19 only on the afternoon of February 22.
S’pore’s health officials have explained that Case 91 slipped through the cracks because her condition and travel history did not fit their suspect case definitions at that time, adding that they have since tightened their criteria for suspect cases with no travel history to Covid-19 hotzones.
The presence of these unusual cases in the dataset reflects the aggressive contact tracing regime in place in Singapore. In other countries where resources are under greater strain, or where the government has taken a more relaxed approach, they could have gone undetected.
It is unclear how infectious these unusual cases were when their condition went undetected. They certainly stand out as one of the more complex challenges in the efforts to contain the outbreak.
5.2 NUMBER OF COVID-19 PATIENTS WITH NO SYMPTOMS
On the flip side, we have eight cases (six men, two women) within the first 100 recovered patients who had no symptoms prior to testing positive for Covid-19. They are: Cases 22, 23, 28, 65, 75, 76, 87 and 138.

Four of the patients – Cases 22, 23, 76 and 87 – are Singaporeans evacuated from Wuhan on two separate flights, on January 30 and February 9. They reported no symptoms when they boarded the flight, but were quarantined upon arrival and then tested for Covid-19 as an added precaution. They subsequently tested positive for the coronavirus.
The four locally transmitted cases with no details about the onset of symptoms are part of known Covid-19 clusters in Singapore. But the press releases by the health ministry have given no explanation as to why these patients had no symptoms prior to confirmation of infection.
Patient 138 is another highly complex case – he tested positive on March 6, after he had served a three-week quarantine and was allowed to leave home. The 26-year-old man, who is linked to two clusters involving local churches in Singapore, had to be recalled for further investigations after the positive test. He was given the all-clear on March 9 and discharged. More on this case can be found in media reports [here](https://www.todayonline.com/singapore/gym-safra-punggol-closed-after-user-has-covid-19-gym-employees-stay-home-notice) and here.
I won’t breakdown the data for the symptoms-confirmation period further, as it is not clear to me that gender and age would be more important in this context than, say, a person’s recent social activities. There’s probably a more scientific way to study this tricky pre-infection-confirmation phase, and that’s better left to the experts.
The notebook and data for the charts in this post are in my Github repo. Let me know if you spot errors or do something interesting with this small dataset from Singapore. Ping me at:
Twitter: Chua Chin Hon
LinkedIn: www.linkedin.com/in/chuachinhon
Note from the editors: Towards Data Science is a Medium publication primarily based on the study of data science and machine learning. We are not health professionals or epidemiologists, and the opinions of this article should not be interpreted as professional advice. To learn more about the coronavirus pandemic, you can click here.