Will there be spikes but no new waves?

Note:  Over the past few months there have been several posts that looked at surges in the number of cases.  For example, the one on 5 May viewed the surge from 5 different angles to assess whether the surge would turn into another wave.  This post is another perspective of assessing why the spike would not turn into another wave. 

I guess I should start by clarifying what I meant as "spike" and "wave"

• I consider a spike as a sudden short-lived increase in the number of cases.  Under this scenario, there is unlikely for any exponential growth

• A wave would be a prolonged increase in the number of cases.  There is a danger that if not managed well, this could lead to exponential growth requiring possibly another lockdown

The chart below illustrates the difference

Over the past few days, there has been a spike in the number of cases

• It was 62 cases on 7 Sept up from 6 cases the day before

• It went further up to 100 cases on 8 Sept

• But it came down to 24 on 9 Sept

The sudden surge was due to 2 new clusters - Benteng Lahad Datu and Sungai.

It is not the end of the story for these 2 clusters because as of 9 Sep because there are still people waiting for test results 

• 1307 people from the Benteng cluster

• 619 people from the Sungai cluster

And this is assuming that there will not be another generation of infection from these clusters

So will the current surge in the number of cases be a spike or the start of another wave?

Second surge

This is the second major spike in the number of cases since the Tabligh event in Mac of this year.  

As can be seen from the chart of weekly cases since the start of the infection, the last spike was towards the end of May due to the infection among the detainees. 

The current spike is slightly different as it is due to two separate clusters happening together

• Those in the detention centres - Benteng Lahad Datu cluster

• A large cluster in Kedah - Sungai cluster

The May detention spike did not lead to an increase in the number of cases among the general public as it was confined to those in the detention centres. I suspect that the contact tracing and isolation of the staff in the detention centres also help to contain the spread.

Along the same lines, there is unlikely to have any large transmission from the Lahad Datu cluster to the general public since most of the cases were among the prisoners - of the 66 tested positive, 64 were prisoners.

The Sungai cluster is more challenging as the index case was a healthcare worker at a private medical centre.  It managed to spread to the index case families and colleagues.

There are two questions with the current spike

• Will we continue to see new spikes in future - my answer is yes

• Will the spikes be contained especially if it is not due to cases in a detained environment - again it is likely to be contained.  In other words, I don't expect an exponential growth

Further Spikes in Future

My rationale on why we would continue to see spikes in the future is based on the following

• The virus has not been eliminated in Malaysia.  Accordingly, there will always be some local who gets infected (hereinafter referred to as index case)

• Malaysia has a targeted testing programme.  As such unless the index case is part of the targeted testing group (eg those in the old folk's homes, healthcare workers, those undergoing surgery) there is the possibility that the index case would infect other before he/she falls sick enough to seek treatment.  Worst would be for the index case to be asymptomatic as more people would be infected before the cluster is detected. 

• Given the 1 to 2 weeks incubation period and/or the 2 to 3 weeks treatment period (for the asymptomatic cases), it is likely that a cluster would form

• Eventually, someone from this cluster would seek treatment.  At this juncture, MOH would get into the picture and commence contact tracing and testing of all the contacts.

• The cluster would be identified and the number of people in the cluster would depend on the time the index case became infected to the time testing of the contacts was done.  Historically, it can be as few as 3 cases to as high 100 cases.

• The high numbers would cause the spike

In summary, we would have periodic spikes because of our targeted testing programme.  

Having said that, there is a mystery on why the healthcare worker in the Sungai index case did not get detected earlier as healthcare workers are part of the targeted group.

Containing the spike

Before answering this question, it is instructive to see why we had the MCO in March. 

The MCO was instituted due to several reasons

• The number of index cases due to the Tabligh event was too great for our contact tracing team then to handle.  Besides the authorities had an initial problem identifying all the people who attended the event.

• At the same time, there was concern that there could be a new wave from those returning to Malaysia after going overseas for the school holidays.

• In March the virus was still new and I suspect the authorities were still trying to address the medical treatment capacities. The MCO was seen as a way to flatten the curve to be below the treatment capacities. 

We managed to bring the virus under control with the MCO.  But don’t forget that during the MCO, there was a lot done to trace those infected and to quarantine them and their contacts.

At the same time, the new wave from those coming back did not arise

Today, we are unlikely to see another exponential growth because

• We have the contact tracing SOP (eg recording of visitors, MySejarhtera, etc) and so we should not have any issues with contact tracing

• Secondly, there are still restrictions for large gathering so any infections would be limited to small groups.  This makes contact tracing and isolating the infected more manageable

• The authorities have used the EMCO to restrict movements in critical areas to assist testing.  I expect this will still be used in a future surge in cases. 

• Our protocol of isolating all - index cases, contacts - will limit the transmission from the cluster to the general public.

Misc

There are two other practices that will help to keep the number of cases in Malaysia low and indirectly reduces the prospects of infections - ie no infections = no spike or wave. 

• We have the 14 days quarantine measure for incoming visitors. Hopefully, this will reduce new sources of infections

• We test enough as shown by the low positivity rates. The positivity rates for the current spike is lower than those for the May spike.  

Item	Period	No of cases	No of tests	Positivity
May spike	14 - 27 May	840	248,223	0.34
Current spike	27 Aug - 9 Sep	262	141,417	0.19

If you want a comparison, the current positivity rates in the US is double digits % whereas in Malaysia we are talking of less than 0.5 %.

Conclusion

Malaysia is one of the few countries that have brought the number of cases below 5% of the peak.

Having achieved this, we will have occasional spikes because we do not conduct mass testing.

Nevertheless, when a cluster is detected, MOH contact trace and test all and this protocol will ensure that the surge in cases does not turn into a wave ie we will not have exponential growth.

This will mean that while there will be the occasional spikes, there will not be another wave. 

- - - - - - - - - - - - - - - - - - - - - - - - - - -

Be fearless to get more to Stay Safe, Share this Blog

PS: This blog is for me to better understand COVID 19 as this will impact my investments. If you are also into equities, follow me at i4value.asia

Disclaimer:  I am not an epidemiologist, healthcare worker, pharmacist, or staff in the Ministry of Health, but rather is someone with a strong interest in numerical analysis.  The content is an attempt to understand what is happening in the battle against COVID 19 from a data-based perspective. The opinions expressed here are based on information extracted from readily available public sources but I do not warrant its completeness or accuracy and should not be relied on as such.