Health experts estimate the number of infections in this outbreak could reach 4,500 or 6,600 depending on the level of social distancing and reduced contact.
Independent experts, led by Dr. Nguyen Thu Anh, from the Woolcock Institute of Medical Research (specializing in lungs) of the University of Sydney, said: This outbreak could start from mid-April 2021 or earlier. . When the first Covid-19 case was detected, the number of cases increased rapidly, as of May 20, 1762 cases were recorded and spread to 30 provinces/cities, and many rounds of infection appeared. This proves that there have been silent cases of Covid-19 in the community.
According to the research team, the fourth wave of epidemics appeared with many simultaneous outbreaks, originating from imported cases that were not strictly isolated or illegally entered. The results of gene sequencing of some cases showed that the virus strains were variant B.1.167.2 (India) and B.1.1.7 (UK). These are new strains of virus appearing in Vietnam.
When infected with nCoV from imported cases, people come for medical examination and unknowingly spread the virus in hospitals. The hospital became an outbreak and continued to spread to the community. This contagion process went through many rounds. Below is an example of an infection chain through at least 5 rounds of the outbreak at the Central Hospital for Tropical Diseases 2.
On May 4, a cluster of infections at the Central Hospital for Tropical Diseases was discovered after a hospital doctor who went on a business trip abroad tested positive for nCoV. By May 11, the Central Hospital for Tropical Diseases had detected more than 60 Covid-19 patients, including medical staff, patients and patients’ family members at the hospital. From the cases at the Central Hospital for Tropical Diseases, a cluster of 11 infections quickly appeared at the K Hospital at Tan Trieu campus.
From chart 1 shows, when the functional forces were implementing tracing measures at the Central Hospital for Tropical Diseases 2 and Hospital K, the infection chain reached Bac Ninh and Lang Son, then spread to Hoa Binh. Binh and Bac Giang.
According to the research team, outbreaks located in hospitals can be controlled by isolation measures. However, outbreaks related to places where many people gather, large industrial zones, and sensitive activities such as bars and karaoke are complex and difficult to fully trace.
“Therefore, cutting the infection chain to limit new outbreaks is more complicated and needs to be done faster and more thoroughly,” the study emphasized.
From chart 2, this outbreak shows that as of May 11, many outbreaks have appeared simultaneously with about 20 infection chains. The first was from Da Nang with the case in the isolation area returning to Ha Nam and New Phuong Dong Bar, AMIDA Beauty Salon; followed by outbreaks in Yen Bai with cases from Indian experts, infecting Chinese experts, spreading to Vinh Phuc and some localities…. Then there were strong outbreaks in Vietnam. Central Tropical Hospital 2, Hospital K, … spread to many localities, continuing to attack hospitals and industrial zones in Bac Giang and Bac Ninh provinces…
Not only many outbreaks, but the relationship of outbreaks is quite complicated, overlapping with each other. From the outbreak at the Central Hospital for Tropical Diseases (blue) to the cases at the K hospital (orange), additional image of the infection chain at Vinh Phuc Hoa Sen Health Care Center (red) …
For example, from an infection case at the Central Hospital for Tropical Diseases, “patient 3171” infecting family members is ca 3181 male, 58 years old, address in Phuc Tho district, Hanoi announced May 8.
Patient 3181 continues to be the source of infection for “patient 3253”, 74 years old, residing in Hiep Thuan commune, Phuc Tho district. From “patient 3253” begins a new cluster of infections including “patients 3387-3389”.
Also from the outbreak of the Central Hospital for Tropical Diseases, Nam Dinh Province recorded 1 case, patient 3229, female, 16 years old, address in Truc Ninh district. This case is also epidemiologically related to patient 3166 at Tan Trieu K Hospital. This patient continued to infect patient 3228, from here another chain of infections at Hoa Sen Health Care Center….
Forecasting the development of this epidemic, the research team proposed two scenarios according to the SEIQHCDR epidemic forecasting model using epidemiological, clinical and sociological data of Vietnam, with reference to data meta-analysis. from countries around the world. This model has been verified with the second two outbreaks (in Da Nang) and the third (Hai Duong), giving high accuracy results, the error is less than 5%.
Scenario one is the current scenario: It is assumed that we keep the current epidemic prevention measures such as tracing, concentrated isolation, medical isolation in epidemic areas and social distancing in high-risk areas (reducing social contact at a low level). 20% from 4/5 and 50% from 9/5.
With this scenario, the peak of the epidemic is in the week of May 3-4, 2021 with the number of infections per day possibly up to 150-210 cases (this is the actual number of infections in the community, not the number of detected and reported cases). fox). The epidemic could end in mid or late June 2021 with a total of 4,100 to 6,600 infections. However, because the research team did not have enough detailed epidemiological information on the disease outbreaks in the industrial zone in Bac Giang, this estimate may not accurately reflect the serious situation of the epidemic.
At the same time, if social distancing is not timely, the pathogen will spread silently and create large outbreaks simultaneously in many provinces and cities.
Scenario 2 – best scenario: Implementing social distancing, reducing contact on a provincial and municipal scale with high-risk provinces, the number of new infections increased rapidly (reducing social contact at 20% from May 4, 50% from May 9 and 60% from May 24). The peak of the epidemic is still at the week of May 3-4, but the epidemic may end 10 days earlier with fewer cumulative cases, ranging from a total of 2,900 – 4,500 cases.
Research team proposes anti-epidemic measures According to the principle of switching from epidemic prevention to attack by a strategy of testing and screening combined with epidemic response at 4 levels and rapid coverage of the Covid-19 vaccine.
Proactively detect potential cases/outbreaks by screening tests to find cases. The earlier cases are found, the less tracing and blockade are required.
Localities can actively self-activate timely and flexible levels of epidemic prevention and control according to the following levels:
Level 1: There have been no cases of Covid-19 in the community, implemented 5 K measures and strictly managed the isolation area. Testing all people in high-risk groups such as medical staff, quarantine staff weekly, All service staff such as airports, bus stations, goods delivery… every 2-4 weeks; All people showing signs of cough/fever, Implement a broad testing strategy until Covid-19 vaccine coverage is 70%.
Level 2: When there are 1-3 community cases in a district in the past 14 days, or there is a chain of transmission to F2 with a clear source of infection, or only one outbreak is detected. In the district/district with cases, implement blockade of villages/neighborhoods, neighborhoods, factories with cases. Trace and isolate as is.
Perform testing of all people in high-risk groups such as medical staff, isolation area staff, service staff such as airports, bus stations, delivery of goods… weekly, all patients and people signs of cough/fever. Testing the entire population in the blockade area, can be tested for pool or antigen test every other day.
Implement measures to limit mass gatherings for at least 2 weeks until there are no more cases in the community for the previous 14 days.
Thoroughly close non-essential services (bar, discotheque, karaoke, singing services together…). Stop activities with large gatherings when there are 20 or more people participating, Reduce the frequency of traveling to other localities.
Allow essential service establishments to open if they strictly implement epidemic prevention measures such as washing hands, wearing masks, distancing themselves, and recording customer lists. Strictly monitor the implementation of 5K. This corresponds to a 40% reduction in exposure. There are no cases in the district as level 1.
Level 3: When there are 4 to less than 10 cases of disease in the community in a district in the past 14 days, or there is at least one case with no detected source of infection, or there are 2 or more outbreaks in 2 communes/wards above.
In a district/district with a case, a blockade of villages/neighborhoods, neighborhoods, factories with cases or industrial parks with more than one factory has cases is implemented. Trace and isolate as is.
Testing all people in high-risk groups such as medical staff, isolation area staff, service staff such as airports, bus stations, delivery of goods, etc. weekly, all patients and people with signs of cough/fever; Test the entire population in the blockade area (pool test or antigen test every other day).
Measures to limit mass gatherings are below for at least 2 weeks until the number of cases in the community is <4 in the past 14 days, and gradually move to levels corresponding to the above epidemic situation.
Stop activities with large gatherings when there are 5 or more people participating. Stopping business services that require people to come into contact with people (especially entertainment services such as bars, discos, karaoke, singing services, gyms, cinemas), except services. essential service. Suspension of pedestrian streets. Stop going to school, do online study/exam. Limit travel to other locations. Encourage people to only leave their homes when necessary. Encourage telemedicine where possible.
This level of distance corresponds to a 60% reduction in exposure. In other districts, the above classification applies.
Level 4: When there are 10 or more cases of the disease in the community in the past 14 days, or self-identified as having limited epidemic prevention capacity. In a district/district with a case, a blockade of villages/hamlets, quarters, factories with cases or industrial parks with more than one factory has cases will be blocked. Trace and isolate as is.
Testing all people in high-risk groups such as medical staff, isolation area staff, service staff such as airports, bus stations, delivery of goods, … weekly, all patients and people with signs of cough/fever. Testing of the entire population in the blockade area can be combined with testing or antigen testing on alternate days.)
Measures to limit mass gatherings for at least 2 weeks until the number of cases in the community is less than 10 cases in the past 14 days and gradually move to levels corresponding to the above epidemic situation. Ask people to only leave the house when it is necessary.
Stop activities, close gathering services. Stop moving out of town. Stop business services except essential services. Close schools. Encourage telemedicine where possible. This distance corresponds to an 80% reduction in exposure.
In addition, according to the research team, mapping the risk of spread and prevalence of virus strains is also essential. The epidemic has appeared in many localities, so timely and accurate reporting will help identify and forecast the epidemic situation more accurately. From there, make decisions on preventive measures and choose appropriate vaccines.
Restrict entry to nationals residing in countries with endemic or emerging strains of the virus.
For the vaccine strategy, use only vaccines with scientific evidence that are highly effective against viruses circulating in Vietnam such as Pfizer & BioNTech, Moderna, Astra Zeneca). As the circulating epidemiology of virus strains changes, appropriate vaccine strategies need to be changed. Using vaccines with low effectiveness will create subjective psychology in vaccinated people, leading to a greater risk of outbreaks. It is necessary to start ordering vaccines for children as soon as possible and based on the results of clinical trials around the world.