Saturday, January 23, 2010

Half of schoolchildren in some areas had swine flu: government scientists

Up to half of children in some areas have had swine flu even though they may not have shown symptoms, government scientists have found.

Thursday, November 26, 2009

Up to a third of children in some areas have been infected

Fergus Walsh | 16:54 UK time, Tuesday, 24 November 2009

It's been one of the big questions of this pandemic. Just how many of us in Britain have actually had swine flu?
Knowing that would be incredibly useful, as the bigger the proportion infected, the further we are into this pandemic and the less likely there will be a further sting in its tail.

The Health Protection Agency (HPA) has done blood tests of hundreds of children and parents connected to early school outbreaks.
With one school in south west England they tested around 500 people. They found that although around one in 10 children fell ill, three to five times as many got infected and developed antibodies.
After analysing this and other data relating to the number of children being seen by GPs, the HPA has now come up with these interesting estimates:

• Up to one third of children in swine flu hotspots (such as England and the West Midlands) have already been infected with the H1N1 virus.
• Across the UK up to one in five children has had had swine flu.
• About half of those who get infected show no symptoms.

This is all very reassuring. Professor Maria Zambon from the HPA said:
"We didn't get the pandemic that we planned for and you might say that we've been lobbed a soft ball. There hasn't been high case mortality, the virus is sensitive to drugs, and we've been able to make vaccine and roll it out. I am incredibly grateful that we are not dealing with a pandemic of H5 (bird flu)."
Professor Zambon said the virus had had a relatively low impact on older adults and that was probably explained by pre-existing immunity. The HPA has these estimates:

• For those aged over 50 up to four in 10 people have pre-existing protective antibodies to the H1N1 pandemic virus.
• If you are under 50 it falls to around one in 10 of the population.

The professor, who is an acknowledged world expert on flu, did utter a few words of caution. "Influenza is full of mystery and intrigue. It has lots of twists and turns" and she predicted that mutations of the swine flu virus should be expected. She also pointed out that there could still be a substantial outbreak of seasonal flu over winter.

Sunday, November 1, 2009

WHO: Swine flu jab as safe as seasonal vaccine

Fergus Walsh | 16:56 UK time, Friday, 30 October 2009
Many readers of this blog may be about to get a letter from their GP offering them a vaccine against H1N1 swine flu, or will receive an invitation in the coming weeks, if they fall into specific at-risk groups.
If so, they may well be interested in the latest advice from the World Health Organization(WHO).

A nurse prepares a dose rate of H1N1 swine flu vaccinationThe experts who advise the WHO and governments about immunisation have said that the H1N1 pandemic vaccines appear to be as safe as seasonal flu jabs.
The Strategic Advisory Group of Exerts (SAGE) on immunisation met earlier this week to review both clinical trials involving several thousand volunteers and the ongoing mass immunisation campaigns being conducted in at least 14 countries where several hundred thousand doses had been administered.

Details of its decision were released by the WHO.
This is what it says about vaccine safety and the use of the vaccine in pregnant women:
"The experts reviewed early results from the monitoring of people who have received pandemic vaccines and found no indication of unusual adverse reactions. Some adverse events following vaccination have been notified, but these are well within the range of those seen with seasonal vaccines, which have an excellent safety profile. Although early results are reassuring, monitoring for adverse events should continue.

"Concerning vaccines for pregnant women, SAGE noted that studies in experimental animals using live attenuated vaccines and non-adjuvanted or adjuvanted inactivated vaccines found no evidence of direct or indirect harmful effects on fertility, pregnancy, development of the embryo or foetus, birthing, or post-natal development.

"Based on these data and the substantially elevated risk for a severe outcome in pregnant women infected with the pandemic virus, SAGE recommended that any licensed vaccine can be used in pregnant women, provided no specific contraindication has been identified by the regulatory authority."
At a subsequent briefing, Dr Marie-Paule Kieny, WHO Director of the Initiative for Vaccine Research said:
"All the reports received to date... have shown that the safety profile of this pandemic vaccine is good and is very similar to the one known for seasonal flu vaccine. Nothing special about adverse events has been noted.

Therefore SAGE has considered that in view of the particular importance to vaccinate pregnant women who are at significantly higher risk of severe adverse outcome following infection with a pandemic virus, especially in the second and third trimester of pregnancy, that these women can be vaccinated with any of the licensed vaccines."
Pregnant women and young people

I would like to quote another section of the SAGE advice as it highlights the increased risks facing both pregnant women and the young:

"Globally, teenagers and young adults continue to account for the majority of cases, with rates of hospitalization highest in very young children. Between 1% to 10% of patients with clinical illness require hospitalization. Of hospitalized patients, from 10% to 25% require admission to an intensive care unit, and from 2% to 9% have a fatal outcome.

"Overall, from 7% to 10% of all hospitalized patients are pregnant women in their second or third trimester of pregnancy. Pregnant women are ten times more likely to need care in an intensive care unit when compared with the general population."

What stands out for me is the greatly elevated risks among pregnant women.
Pregnancy leads to changes in the immune, respiratory and cardiovascular systems and it has always been a risk factor for seasonal flu, but nothing like the potential threat posed by this pandemic strain.
Bear in mind, though, that since the outbreak began, the number of deaths from swine flu has been very low compared to seasonal flu (which mostly kills the frail elderly). The latest global death toll is 5,700 up around 700 in the past week.
This can be partly explained by the start of the northern hemisphere flu season. But set that against the fact that many millions of people worldwide had been exposed to the virus (around 500,000 in Britain alone).
All these figures are estimates only, but they help in setting in context the level of risk. The availability of a vaccine means that this is now a preventable disease.
SAGE said both the pandemic and seasonal flu vaccines can be given at the same time. As with the UK recommendation, it said one dose of vaccine is enough to protect those from 10 years of age.
For those older than six months and under 10, it says data are limited and more studies are needed. The UK is giving two doses, spaced three weeks apart to those under 10, but only to children in at-risk groups.
But as I said in my previous post, it seems just a question of time before this is extended to all children. SAGE had this to say:
"Where national authorities have made children a priority for early vaccination, SAGE recommended that priority be given to the administration of one dose of vaccine to as many children as possible."
When you bear in mind that SAGE is chaired by Professor David Salisbury, who is also the head of immunisation at the Department of Health, it appears to be a further pointer towards an eventual move to the mass immunisation of all children in the UK.

Friday, October 16, 2009

Vaccination gets the green light

Fergus Walsh | 17:42 UK time, Friday, 16 October 2009

The long-awaited UK-wide programme of vaccination against H1N1 swine flu will begin next week.
The first to get immunised will be the most vulnerable people in the population - namely, high-risk patients in hospital (for example, those with leukaemia who have a weakened immune system).
The Chief Medical Officer for England, Sir Liam Donaldson, who is the government's main advisor on tackling the virus, gave further details (for England) at his weekly press briefing.

The GSK vaccine Pandemrix has become the jab of choice for the NHS, despite the government also buying stocks of a second vaccine Celvapan, from another manufacturer, Baxter. This is partly due to production problems with the Baxter vaccine.

Sir Liam Donaldson urged at risk groups, including pregnant women, to get immunised:
"I don't want to see anyone dying of an illness that can be prevented by vaccination. Only this week we have seen two deaths among pregnant women: one in Scotland and another in Wales."
The head of immunisation at the Department of Health, Professor David Salisbury, said those over 10 years of age would need just one dose of Pandemrix vaccine, because clinical trials had shown that it was sufficient to offer good immunity.

Those under 10 will need two jabs, spaced three weeks apart, because their immune systems don't respond as well.

By contrast, anyone who has Celvapan will require two doses. Professor Salisbury said he specifically wanted pregnant women to have the Pandemrix GSK jab, because it meant they would be protected quicker. He said:
"If a pregnant woman has an interval of three weeks to wait for immunity to kick in, that could put the pregnancy at risk, so it is seriously beneficial for them to be protected after one dose of Pandemrix."
Professor Salisbury pointed out that both vaccines had been licensed and were safe. The Baxter vaccine, which is not made using eggs, would be used for those who have a rare egg allergy. The key difference between the two vaccines is that Pandemrix has an adjuvant, or booster chemical, which is designed to boost the body's immune response.
Adjuvanted flu vaccines have been around for at least a decade, but there is not nearly the same degree of clinical data as with unadjuvanted flu jabs.

Because of the lack of clinical data, the WHO suggested in July [267KB PDF] that swine flu vaccines without adjuvants, should be used in pregnant women, where possible.
This suggestion came from the influential Strategic Advisory Group of Experts on Immunization (Sage). That would have meant Celvapan being used, not Pandemrix.

But Professor Salisbury, who chairs Sage as well as being the head of immunisation at the Health Department, indicated that this advice was now out of date.
"It was made before the GSK vaccine was licensed and based on what we knew at the time. The regulators were able to look at studies involving pregnancy in animals and at other clinical data."
SAGE meets in two weeks and is expected to revise its earlier guidance. So what should pregnant women do?
The clear advice is that those who are pregnant should be immunised because they are at considerably higher risk, as a result of the body's natural suppression of the immune system.
The further along the pregnancy, the greater the risk to the mother and her unborn child. Earlier this week, a pregnant teenager in Scotland died after contracting swine flu, leading to the death of her unborn child. Recently, a new mother in Wales died two weeks after giving birth following infection with the virus.

Many will want to find out as much information as possible about Pandemrix before agreeing to be immunised. There have been clinical trials - including data published today.
To date, 2,000 people have received the jab. None of those was pregnant because ethical committees will not usually allow pregnant women to take part in trials.
So what is in the adjuvant, known as AS03, found in the GSK jab? The key ingredient is something called squalene, which is derived from fish oil. The World Health Organization has an explanatory note on this.

Squalene (wikipedia) has been used in flu vaccines before, as the WHO makes clear:
"22 million doses of Chiron's influenza vaccine (FLUAD) have been administered safely since 1997. This vaccine contains about 10mg of squalene per dose. No severe adverse events have been associated with the vaccine."

and WHO say

Are squalene-containing vaccines safe?

  • Over 22 million doses of squalene-containing flu vaccine have been administered. The absence of significant vaccine-related adverse events following this number of doses suggests that squalene in vaccines has no significant risk. This vaccine has been given primarily to older age groups.
  • As this vaccine and new squalene-containing vaccines are introduced in other age groups, post-marketing follow-up to detect any vaccine-related adverse events will need to be performed.

Saturday, October 10, 2009

"Lucky break" slows spread of swine flu - Donaldson

Chief medical officer now optimistic about the scale of the epidemic
Britain's swine flu outbreak is slowing down, possibly as the result of a "lucky break" in the way the virus has behaved, the chief medical officer said today.
Sir Liam Donaldson, who has been generally cautious in his weekly predictions on the likely course of the epidemic, was more optimistic as he suggested during a news conference that the peak number of cases may be lower than previously thought.
The rate of increase looks to be nothing like the weekly doubling of cases that experts had predicted. Last week, there were 18,000 new cases of swine flu, rising from 14,000 the previous week and 9,000 the week before that.
"We are well into the second wave of pandemic flu, having had the first wave in July, but it's proving so far to be a slow burner," Donaldson said. "It's possible that it might peak at a lower level – and an earlier level – than expected which would be incredibly positive news.
"It means we could get the vaccine programme well under way. If this virus has another peak up its sleeve, as in 1968, we might be able to avert that completely."
"We may have got a lucky break in how the virus has behaved at the start of our flu season and we may be able to get the vaccine out there before our flu season really gets under way," said Donaldson. "I'm looking at it very optimistically."

The body which advises ministers on vaccination - the Joint Committee on Vaccination and Immunisation - has been meeting today and a key point of discussion has been whether to extend H1N1 swine flu vaccination beyond at-risk groups. If this does happen, it would be healthy children who would be the first group targeted, on the grounds that children are the most likely to catch the disease, and the most likely to require hospital treatment.
Vaccination against seasonal flu has already begun in many parts of the UK and swine flu jabs will be sent to GPs from later this month. Sir Liam said:
"There's been a supply of half a million doses of Baxter vaccine in warehouses for some time. We expect to get considerable numbers of the GSK vaccine quite soon. The only doses here so far (of the GSK vaccine) have been for clinical trials and there hasn't been a major delivery yet."