By Tan Kwee Yong, Lecturer at Sunway College
The COVID-19 has been with us since the end of the year 2019 and all countries are still fighting it. Vaccines have also been introduced and are taken as the sole solution to curb the pandemic.
Despite the effort to improve the vaccination rate which can also lower the death rate, the vaccination program remains unpopular in the western countries. Nonetheless, this barrier will be overcome in the near future since all relevant parties are putting extra effort into it.
However, it is also undeniable that the rapid mutation of the nasty coronavirus has resulted in many other variants. It is no surprise that more Greek letters will be introduced soon. The virus has evolved to be more resilient and highly infectious.
The recent outbreak in the already highly-vaccinated population in China, Singapore and United Kingdom had also confirmed the infection rate of the mutated virus in the local community and alarmed the governments, who had moved to enforce the administration of a booster shot due to the wearing effect of the vaccine after a certain period (normally 6 – 9 months).
This has also encouraged governments and public to be extra vigilant about the efficacy of the vaccines against these virus variants which may once again delay the recovery of the already weakened economy after the never-ending nationwide and local lockdowns and standard operation procedure (SOP) revisions.
As more studies were carried out on this coronavirus, it has been confirmed that it can be transmitted through droplets and direct contact.
On the other hand, more coronavirus related antimicrobial studies has also been initiated. Among these, the silver-based, titanium-based, copper-based and polymeric antimicrobial materials are the most reported as materials with most efficacy.
The first three metal based antimicrobial materials work effectively for hard surfaces, hardware, devices, etc while the polymeric antimicrobial materials are for on textiles, fabrics, food packaging, etc.
The mechanisms to suppress the microbial activity involved in these materials are normally categorised into two: resistance and annihilation. The resistance mechanism creates a hostile environment which stops the growth and attachment of microbes to the host materials while the annihilation mechanism releases active ions (e.g. copper and silver ions) to kill or deactivate the active cells in microbes.
Immediately after the thoughts of using antimicrobial materials in public areas were forwarded last year (“Time to consider antimicrobial materials in public places”, BERNAMA), the Ministry of Health had also reported similar observation on the efficacy of the use of antimicrobial materials against human coronavirus, especially copper or copper contained materials. It has been found that the coronavirus can remain viable on stainless steel and plastic surfaces and remains detectable even up to 72 hours. It can also remain viable on cardboard for up to 24 hours but only viable on copper surfaces for only 4 hours.
In addition, the inactivation of coronavirus occurs rapidly and effectively on pure copper and all copper-containing surfaces including brass (copper and zinc), bronze (copper and tin) and other copper alloys. The inactivation rate is found to be directly proportional to the copper content in the material. Out of these copper-contained materials, brass is the most recommended for general application. This is because it is malleable, easy to cast and relatively cheap. Brass can be used as decorative components and also replacements for the current widely used stainless steel with its self-disinfecting ability.
Besides common hard contact surfaces, another frequent contact surface to consider would be food packaging material. It is normally contaminated with numerous microbes due to improper handling. Only a handful of antimicrobial food packaging materials are commercially available in the market and limited information can be retrieved.
Currently, polypropylene (PP) (a common synthetic polymer) is used as the main food packaging material. The antimicrobial properties of polymer are defined by its ability to stop microbial activities on its surface with and without the load of virus. Polymer has a broad-spectrum antimicrobial effect (or the resistance mechanism aforementioned) which can block all microbes at entry and prevent microbes from further travelling into food and be consumed accidentally. This means that PP can successfully keep the microbes outside of the container but it cannot self-disinfect, and therefore the outer surface has to be sanitised. Furthermore, people can choose to take away more often without worrying about the increase of the usage of single-use plastic which also pose greater harm to the environment. As such, scientists are now working on the natural-based polymers using chitin and chitosan that come with self-disinfecting abilities.
In order to protect people from getting infected easily, the use of antimicrobial material should be further encouraged. This way, a safer environment can be created, to not only protect our vulnerable generations, but also to minimise the more significant spread of the coronavirus in high density areas like shopping malls, offices and apartments where scheduled sanitisation is not sufficient, especially on frequent contact surfaces like hand rails and lift buttons in the public areas. Furthermore, this also aligns with the governments’ interest in keeping the economy open and keep the public free from fear by minimizing the anxiety from of contact-acquired infections.
