… this week pivotal to understand impact of relaxed measures

The effective reproduction ratio for Covid-19 in Malta stands at 0.65, but this week is a pivotal one to understand impact of new measures, statistician Vincent Marmara told The Malta Independent.

The reproduction ratio of the virus is one of the key figures which countries across the world have been trying to reduce ever since the Covid-19 pandemic began. The aim for countries has been to reduce the ratio to a level of 1 – which would mean that one person would transmit the virus to one other person.

With the number of cases sharply declining and then stabilizing at a low number for the past three weeks, the reproduction ratio had stood at around 0.5 – but after an increase in cases over the past two days – Sunday saw 6 new cases, while Monday saw 7 new cases compared to an average 3 cases everyday over the past three weeks has seen an increase in the reproduction ratio.

Much has been said of that increase, however Marmara said that things must be taken into perspective and note that certain restrictions have been reduced.  He noted that one cannot take the case count of just the last two days and use them to say that the situation has changed. The existences of specific clusters within these cases must also be taken into account as well, Marmara observed.

The reproduction ratio, he explained, is calculated based on an SEIR model wherein a particle filter algorithm is used to ascertain the most accurate reproduction value based on the case numbers.

The first set of restrictive measures put in place to mitigate the spread of the virus were relaxed as of 4 May – now eight days ago – with non-essential retail outlets being allowed to open, certain medical procedures continuing, and travel between Malta and Gozo re-opened.  Other measures to mitigate the spread were put in place on the same day, chief amongst those being the mandatory wearing of facemasks or visors when entering all shops and when using public transport.

Marmara said that a number of days must pass before the true impact and effect of the relaxation of these measures has, namely due to the average five to six-day incubation period of the virus and the time for the test to be done. 

He said that this week is an extremely important one and noted that the effective reproduction number should be followed daily to keep an eye on the spread.

Even though the current reproduction number remains under 1, social distancing and use of protective wear remain extremely important, Marmara said, so that the spread of the virus can be kept low.

With this week being critical, Marmara said that it is important to keep following this value to maintain a clear picture of the situation.

Malta has had 503 cases of Covid-19 since the first cluster of cases was found on 7 March. 434 of those have recovered while 5 of those have unfortunately passed away.  This means that there remain 64 active cases of the virus, with Monday being the first day in a few weeks where the active case count rose slightly.

Report: Albert Galea, Date: 12th May 2020

Source: https://www.independent.com.mt/articles/2020-05-12/local-news/Covid-19-reproduction-ratio-at-0-65-this-week-pivotal-to-understand-impact-of-relaxed-measures-6736223035