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Flu Watch
H1N1 is here. So, how?
Four people found to have the Influenza A(H1N1) virus were quarantined earlier this week, though no new case has been reported since. NG WAN CHING tackles 10 questions to help you better understand the H1N1 flu.
June 01, 2009
1. What's the difference between seasonal flu and H1N1?
They are both influenza A, but seasonal flu and H1N1 are different strains.
The H1N1 North American/human flu hasn't been seen before. That's why the current outbreak is worrying.
Seasonal flu, by definition, is a virus that has been around, so there's ongoing immunity in the community that prevents widespread transmission.
Because H1N1 is a new virus, there isn't community immunity to help stop it from spreading.
2. Why didn't patient zero's boyfriend or the lecturer who sat next to her on the plane get infected?
Not every one who is exposed to the virus will get infected. The US Centers for Disease Control and Prevention (CDC) and the World Health Organisation (WHO) suggested an attack rate of about 30 per cent for H1N1.
This means that 30 per cent of those exposed to the virus will become infected.
Said Associate Professor Leo Yee Sin, head of the Communicable Disease Centre here: 'We have to watch our local contacts closely to understand the transmissibility of this new influenza in the local context.'
3. Is HIN1 more infectious than seasonal flu?
Yes. WHO reported on 11 May that the secondary attack rate of novel H1N1 ranges from 22 per cent to 33 per cent, in contrast with seasonal influenza which ranges from 5 per cent to 15 per cent.
Secondary attack rate is a measure of the frequency of new cases of a disease among the contacts of known cases.
4. Of those exposed to the H1N1 virus in S'pore, what percentage will get infected?
Singapore will have to wait and watch the local close contacts of H1N1 cases to assess what the attack rate here will be.
It may depend on how effectively steps like contact tracing and quarantining can reduce the risk of their getting the disease.
'We need to take into consideration the effect on intervention, that is removing the onward transmission risk from the index cases to their close contacts,' said Assoc Prof Leo.
5. After so long being H1N1-free, S'pore saw four cases in two days. Is there a reason for this?
This probably reflects how quickly the virus is spreading in the at risk areas and the frequency at which people are travelling from these areas to Singapore.
6. Has H1N1 started spreading in the community here?
As of yesterday, no. Since the WHO sounded the alarm five weeks ago about a novel virus, the Ministry of Health has increased its sampling of upper respiratory tract infections here.
It has been testing 1,000 samples from the community a week. So far, no novel virus has yet been found in the community.
7. When is a person with H1N1 infectious to others?
The viral shedding generally starts a day before symptoms start and continues for a week. Viral shedding peaks around 24 to 72 hours.
Children and severely ill patients generally shed for a longer period of time.
An individual can infect others even before symptoms start and is most infectious during peak viral shedding.
'This is still an area that requires more studies,' said Assoc Prof Leo.
8. Is there any difference between symptoms of seasonal flu and H1N1?
Both seasonal flu and H1N1 come with symptoms of sore throat, cough, fever and body aches. A swab sample must be tested to find out if it's H1N1.
9. Should S'poreans panic when there is community spread of H1N1?
Not if the illness remains mild.
10. Are some people more at risk of catching H1N1 than others?
More study is needed to determine if some (for example, younger or older people, or people with other medical conditions) are more at risk or have a higher risk of severe illness. WHO recommends that everyone take precautions to prevent the spread of infection.
--------------------------------------------------------------------------------
UPDATE
As of yesterday, a total of 119 home quarantine orders (HQOs) were issued.
Of these, 75 HQOs have beenserved, while 44 HQOs arecurrently beingserved.
Of the 75 HQOs served, 43 are still active. The rest have finished their HQOs.
Flu Watch
H1N1 is here. So, how?
Four people found to have the Influenza A(H1N1) virus were quarantined earlier this week, though no new case has been reported since. NG WAN CHING tackles 10 questions to help you better understand the H1N1 flu.
June 01, 2009
1. What's the difference between seasonal flu and H1N1?
They are both influenza A, but seasonal flu and H1N1 are different strains.
The H1N1 North American/human flu hasn't been seen before. That's why the current outbreak is worrying.
Seasonal flu, by definition, is a virus that has been around, so there's ongoing immunity in the community that prevents widespread transmission.
Because H1N1 is a new virus, there isn't community immunity to help stop it from spreading.
2. Why didn't patient zero's boyfriend or the lecturer who sat next to her on the plane get infected?
Not every one who is exposed to the virus will get infected. The US Centers for Disease Control and Prevention (CDC) and the World Health Organisation (WHO) suggested an attack rate of about 30 per cent for H1N1.
This means that 30 per cent of those exposed to the virus will become infected.
Said Associate Professor Leo Yee Sin, head of the Communicable Disease Centre here: 'We have to watch our local contacts closely to understand the transmissibility of this new influenza in the local context.'
3. Is HIN1 more infectious than seasonal flu?
Yes. WHO reported on 11 May that the secondary attack rate of novel H1N1 ranges from 22 per cent to 33 per cent, in contrast with seasonal influenza which ranges from 5 per cent to 15 per cent.
Secondary attack rate is a measure of the frequency of new cases of a disease among the contacts of known cases.
4. Of those exposed to the H1N1 virus in S'pore, what percentage will get infected?
Singapore will have to wait and watch the local close contacts of H1N1 cases to assess what the attack rate here will be.
It may depend on how effectively steps like contact tracing and quarantining can reduce the risk of their getting the disease.
'We need to take into consideration the effect on intervention, that is removing the onward transmission risk from the index cases to their close contacts,' said Assoc Prof Leo.
5. After so long being H1N1-free, S'pore saw four cases in two days. Is there a reason for this?
This probably reflects how quickly the virus is spreading in the at risk areas and the frequency at which people are travelling from these areas to Singapore.
6. Has H1N1 started spreading in the community here?
As of yesterday, no. Since the WHO sounded the alarm five weeks ago about a novel virus, the Ministry of Health has increased its sampling of upper respiratory tract infections here.
It has been testing 1,000 samples from the community a week. So far, no novel virus has yet been found in the community.
7. When is a person with H1N1 infectious to others?
The viral shedding generally starts a day before symptoms start and continues for a week. Viral shedding peaks around 24 to 72 hours.
Children and severely ill patients generally shed for a longer period of time.
An individual can infect others even before symptoms start and is most infectious during peak viral shedding.
'This is still an area that requires more studies,' said Assoc Prof Leo.
8. Is there any difference between symptoms of seasonal flu and H1N1?
Both seasonal flu and H1N1 come with symptoms of sore throat, cough, fever and body aches. A swab sample must be tested to find out if it's H1N1.
9. Should S'poreans panic when there is community spread of H1N1?
Not if the illness remains mild.
10. Are some people more at risk of catching H1N1 than others?
More study is needed to determine if some (for example, younger or older people, or people with other medical conditions) are more at risk or have a higher risk of severe illness. WHO recommends that everyone take precautions to prevent the spread of infection.
--------------------------------------------------------------------------------
UPDATE
As of yesterday, a total of 119 home quarantine orders (HQOs) were issued.
Of these, 75 HQOs have beenserved, while 44 HQOs arecurrently beingserved.
Of the 75 HQOs served, 43 are still active. The rest have finished their HQOs.
