Why do some COVID-19 tests come back with a ‘weak positive’, and why does it matter?


Sheena G. Sullivan, WHO Collaborating Centre for Reference and Research on Influenza and Jennifer MacLachlan, The Peter Doherty Institute for Infection and Immunity

When we get a test result for a disease like COVID-19, we naturally expect it to be either positive or negative. But the results of these tests are not so black and white.

Polymerase chain reaction, or “PCR”, is the most common test to detect the presence or absence of SARS-CoV-2, the virus that causes COVID-19.

Recently, a “weak positive” case of COVID-19 was reported in the Northern Territory.

Let’s take a look at why someone might get a weak positive result.

Shouldn’t you just be ‘positive’ or ‘negative’?

PCR tests are used to detect a range of viruses and pathogens. They look for viral genetic material in a respiratory sample, such as a nose or throat swab or a saliva sample.

We identify a sample to be positive or negative based on the number of times we need to amplify the small segments of genetic material to detect the virus — and whether this number falls below or above a certain threshold.

When there’s a lot of virus present, we only need a few cycles of amplification to detect it. When there isn’t much virus, or there’s none, we need to amplify the sample several more times until finally we cross the threshold and deem the sample negative.




Read more:
The new 15-minute test has potential, but standard tests are still the best way to track COVID-19


So in this process we can see the potential for a weak positive result. It would generally be a reading at or just above the threshold. And that threshold varies depending on the test used.

Importantly, thresholds are just the point at which we believe we’ve detected something. They’re not 100% precise. Sometimes results just above or below the threshold might be false negatives or false positives.

When might you have a weak positive result?

In most cases, the genetic material of a virus is only detectable when we’re infected and the virus is still replicating and shedding into our respiratory passages.

But sometimes, even when the virus is no longer alive and replicating, it can hang around and be detectable by PCR. In these cases, it’s unclear whether the virus is infectious.

A health worker dressed in PPE prepares to take a swab from a man in his car.
PCR tests for COVID-19 look for the genetic material of SARS-CoV-2.
Shutterstock

In the case of the NT man, he had earlier tested positive for COVID-19 in Victoria and recovered. Although he recorded a negative test before travelling to the NT, it’s likely he was still just shedding small amounts of the virus.

This may be more common among people with weaker immune systems, as it takes them longer to clear the virus from their system.

How do we handle weak positives?

A weak positive is treated as a “presumptive positive” result — we presume it to be positive, and generally classify it as such, until we have information to suggest otherwise.

National testing guidelines for COVID-19 recommend weak positive results be checked by testing the same sample again. They also recommend collecting another sample.

In some cases, retesting the original sample may give more confidence of an infection with SARS-CoV-2. But collecting and testing another sample can offer further confirmation.

The subsequent test might target a different region of the virus’ genetic material, or use a different type of test. Alternatively, the sample could be referred to a reference laboratory to verify the result using specialised tests.




Read more:
Goodbye, brain scrapers. COVID-19 tests now use gentler nose swabs


We don’t know of any publicly available data which indicate how common weak positive results are. But we don’t think they’re unusual.

It’s one of the reasons the publicly reported case numbers for COVID-19 are sometimes revised downwards, as weak positives are later confirmed to be negative after retesting.

It’s also not unique to COVID-19 or PCR — many different tests, for a variety of diseases, can produce weak positives.

But the phenomenon has a unique impact when the infection is part of a pandemic.

The danger of assumption

During a pandemic, there are implications not just for the person being tested, but for their contacts, their workplace, and the whole population.

Incorrectly assuming a weak positive result isn’t COVID-19 could lead to a person continuing to transmit the disease to others. It could also prevent them receiving the proper monitoring and, if necessary, treatment.

Conversely, assuming a weak positive result is COVID-19 when it’s actually negative could lead to the person being unnecessarily quarantined, which has potential personal, psychological and financial effects.

A man wearing a mask looks out the open window of his home.
A weak positive result which turns out to be negative could see a person isolated unnecessarily.
Shutterstock

In the case in the NT, classifying this indeterminate result as a positive case would have meant the first COVID-19 infection in two months in that state.

While the man was isolated, NT authorities didn’t count him as a case based on advice from the health department that the result was likely due to residual virus from his previous infection. They said he didn’t have any symptoms and it was highly unlikely he was infectious.

When the elimination of community transmission is being used as a criteria for border closures, individual cases can have significant flow-on effects to the whole population.

For these reasons, it’s important to appreciate the complexities of COVID-19 testing. It’s not always as simple as “positive” or “negative”.




Read more:
Worried you might test positive and put a spanner in Victoria’s COVID roadmap? Here’s why you should get tested anyway


The Conversation


Sheena G. Sullivan, Epidemiologist, WHO Collaborating Centre for Reference and Research on Influenza and Jennifer MacLachlan, Epidemiologist, WHO Collaborating Centre for Viral Hepatitis, The Peter Doherty Institute for Infection and Immunity

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Poll wrap: Labor maintains its lead in Newspoll, while One Nation drops; NSW upper house finalised



File 20190415 147518 debsxo.jpg?ixlib=rb 1.1
With the election season now under way, Labor has retained its lead over the Coalition in the latest Newspoll, though Bill Shorten’s approval rating has not improved.
Lukas Coch/AAP

Adrian Beaumont, University of Melbourne

With five weeks until the May 18 election, this week’s Newspoll, conducted April 11-14 from a sample of 1,700 people, gave Labor a 52-48 lead, unchanged since last week. Primary votes were 39% Coalition (up one), 39% Labor (up two), 9% Greens (steady) and 4% One Nation (down two) – One Nation’s lowest primary vote since November 2016.

While the two-party figure was unchanged, this poll is better for Labor than last week’s Newspoll, with Labor gaining two points in primary votes from One Nation’s drop. If we assess this poll as total right-wing vs total left-wing vote, the left (Labor and Greens) gained two points to stand at 48%, while the right (Coalition and One Nation) lost one point to fall to 43%. Analyst Kevin Bonham said this Newspoll was probably rounded towards the Coalition.

One Nation’s drop is likely the result of increased polarisation between the major parties. If One Nation had been affected by the NRA donations scandal, it would have shown up in last week’s polls.

Nominations for the federal election will be declared on April 24. It is unlikely that One Nation will contest the vast majority of lower house seats. Polling conducted after April 24 is likely to greatly reduce One Nation’s vote as they will no longer be an option for most Australians in the lower house. This reduction of One Nation’s vote may assist the Coalition on primary votes.

In the Newspoll, 45% of respondents were satisfied with Prime Minister Scott Morrison’s performance (steady), and 44% were dissatisfied (up one), for a net approval of +1. Labor leader Bill Shorten’s net approval was steady at -14. Morrison led Shorten by an unchanged 46-35 as better PM.

Since Malcolm Turnbull was ousted as prime minister in August 2018, the Coalition has recovered from a 56-44 deficit in Newspoll to 52-48 this week, due partly to the time that’s passed since the spill and partly to the relative popularity of Morrison.

Now that the election campaign is formally under way, some attention will shift to the opposition’s policies and proposals. The danger for Labor is the Coalition can scare voters about its economic policies, but the potential reward is that Labor can appeal to voters who are frustrated by the Coalition’s perceived inaction on climate change and low wage growth.




Read more:
Post-budget poll wrap: Coalition gets a bounce in Newspoll, but not in Ipsos or Essential


Large difference in voting intentions by age group

Every three months, Newspoll aggregates all the polls it conducted from that time period to get voting intention breakdowns by state, age, gender and region (the five capital cities vs the rest of Australia). For January to March, the overall result was 53-47 to Labor, a point better for Labor than the last two Newspolls.

This three-month Newspoll showed a large difference in voting intentions by age group. Among those aged 18-34, Labor had 46% of the primary vote, the Coalition 28%, the Greens 14% and One Nation 4%. Among those aged 35-49, it was Labor 39%, Coalition 35%, Greens 9% and One Nation 7%. And among those aged 50 or over, the Coalition had 44%, Labor 35%, One Nation 6% and Greens 5%.

It is still important to poll well with this oldest demographic. According to the 2016 census, those aged 18-34 represent 30.3% of the eligible voting age population and those aged 35-49 represent 26.0%. The share of the voting-age population aged 50 or over, however, is 43.7%.

Results by gender were similar. Men gave Labor 40% of the primary vote, the Coalition 37%, the Greens 7% and One Nation 6%. With women, Labor had 39%, the Coalition 37%, the Greens 10% and One Nation 6%. After preferences, Labor would be doing about one point better with women than men.

The best source for state voting intentions is The Poll Bludger’s BludgerTrack. Perhaps reflecting the Coalition’s victory in the recent NSW election, federal Labor’s lead over the Coalition in that state has been reduced to just 50.1-49.9 from about 54-46 in the last few weeks. This is about a 0.6% swing in Labor’s favour from 2016.

Labor has maintained a larger lead in most other states, however. In Victoria, Labor leads by 55.1-44.9, a 3.2% swing to Labor since 2016. In Queensland, Labor leads by 52.0-48.0, a 6.1% swing to Labor. In SA, Labor leads by 55.7-44.3, a 3.4% swing to Labor.

In WA, the Coalition still leads by 51.0-49.0, but this is a 3.6% swing in Labor’s favour from 2016.

Nationally, BludgerTrack gives Labor a 52.5-47.5 lead, a 2.8% swing to Labor.

One Nation wins two seats in the NSW upper house

In the March 23 NSW election, 21 members of the upper house were elected by statewide proportional representation, with a quota of 1/22 of the vote, or 4.55%.

The Coalition won 7.66 quotas, Labor 6.53, the Greens 2.14, One Nation 1.52, the Shooters, Fishers & Farmers 1.22, the Christian Democrats 0.50, the Liberal Democrats 0.48, Animal Justice 0.43 and Keep Sydney Open 0.40.

The Coalition was certain to win an eighth seat, and Labor and One Nation were best placed for two other seats. On preferences, Animal Justice overtook the Liberal Democrats, Christian Democrats and One Nation to win the second-to-last seat, with One Nation’s second candidate, Rod Roberts, defeating the Christian Democrats for the final seat.

It is the first time since 1981 that the Christian Democrats have failed to win a seat in the NSW upper house. David Leyonhjelm, who resigned from the Senate to run as the lead Liberal Democrat candidate in NSW, did not win.

The Coalition now holds 17 of the 42 total upper house seats (down three), Labor 14 (up two), the Greens four (down one), the Shooters two (steady), One Nation two (up two), Animal Justice two (up one) and the Christian Democrats one (down one). One Green member, Justin Field, resigned from the party, and is now an independent.

Overall, the right now holds 22 of the 42 seats. On legislation opposed by the left-wing parties, the Coalition will require support from One Nation, the Shooters and Christian Democrats.




Read more:
Coalition wins a third term in NSW with few seats changing hands


Brexit likely delayed until at least October 31

The European Union leaders have decided to delay Brexit until at least October 31. Without a majority for any plausible Brexit option, the House of Commons could only vote to delay Brexit to prevent a no-deal departure from the EU, but this delay will likely not appeal to the general public or “leave” voters.

Two new polls have the Conservatives slumping to just 28-29% of the UK vote, 4-7 points behind Labour.The Conversation

Adrian Beaumont, Honorary Associate, School of Mathematics and Statistics, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Queensland result, while decided on state issues, adds to Turnbull’s burdens



File 20171126 21798 1dbqne.jpg?ixlib=rb 1.1
The Queensland state election result makes the byelection in Bennelong on December 16 even more important.
AAP/Danny Casey

Michelle Grattan, University of Canberra

The Queensland election was decided overwhelmingly on state factors, as Malcolm Turnbull was quick to say on Sunday, but inevitably it has fallout for the prime minister.

Four implications are obvious in the result, which ABC election analyst Antony Green predicts will be a majority Labor government, while Inside Story’s Tim Colebatch suggests is more likely to be an ALP minority one.

First, it elevates even higher the importance of the December 16 byelection in Bennelong.

Second, it will further unsettle an already depressed and jittery federal backbench.

Third, the federal Queensland Coalition MPs will want greater attention from the government.

Finally, the Nationals – in particular the Queensland Nationals – will accelerate a trend that’s been obvious recently, which is to differentiate their brand.

Bennelong was always destined to be significant, from the moment Liberal MP John Alexander resigned (some government sources think prematurely) in the citizenship crisis. But now that things have gone badly for the Liberal National Party in a state that looms so large for the federal Coalition, the stakes rise.

Turnbull was campaigning in Bennelong on Sunday, falling back on the tried and trusted ground of border protection, claiming that “right now the people smugglers are using Kristina Keneally’s articles, her statements on this, as a marketing tool” (an assertion surely worthy of a factcheck).

He has to get deeply involved in this seat, which is on a 9.7% margin, but the flip side is that the more effort Turnbull puts in, the more he’d be personally identified with a big swing, let alone a loss. On the other hand, if the swing were contained, that would help him.

Psychologically, the Queensland result will send the Coalition’s federal members deeper into the funk caused by the unending run of bad polls and multiple problems engulfing the government. This will accentuate instability and ill discipline, although there is no tangible challenge to Turnbull’s leadership at this point.

The Queensland vote reinforces the now familiar message that people are turned off the major parties. The mid-30s primary votes for Labor (around 36%) and LNP (about 34%) scream disillusionment.

One Nation polled solidly in minor party terms (around 14%) and very strongly in its heartlands, but it couldn’t turn that into the swag of seats it had boasted about. Pauline Hanson’s party fell victim to the inflated expectations it had raised, while the LNP vote fell victim to One Nation.

The result shows the One Nation phenomenon, in terms of its ability to erode the conservative vote, remains a worry, but it does not look like a party on the move.

The Queensland result particularly resonates in Canberra because of how vital that state will be to the Coalition come the election. Federal government members from Queensland will be defensively assertive.

Even before the election, internal chatter had it that senior Queensland Liberal George Brandis would not move out of parliament in the coming reshuffle, as earlier predicted. Revamping cabinet without Brandis while preserving strong Queensland representation would be challenging – and Turnbull could not afford to have Queensland seen to be downgraded.

The federal Queensland Nationals are determined to strengthen their efforts to distinguish themselves from the Liberals and Turnbull.

Nationals cabinet minister Matt Canavan said on Sunday the state result was a “confirmation of how important it is to have a strong National Party at a federal level”.

Nationals MP George Christensen went so far as to issue an apology to One Nation voters. It won’t endear him to Turnbull, but he won’t care. One Nation is on track to win Mirani – from Labor – a seat that adjoins Christensen’s electorate with a small overlap.

He tweeted:

//platform.twitter.com/widgets.js

Queensland Nationals senator Barry O’Sullivan believes the result shows One Nation is not a threat in terms of House of Representatives seats, but highlights the need for the Coalition to fill the vacuum that party has occupied.

“Malcolm can’t do it himself,” O’Sullivan says. Rather, he says, Turnbull has to allow the Nationals to do this.

O’Sullivan is not one who advocates the de-amalgamation of the LNP in Queensland – as some are doing – but a “divisionalisation”, reinforcing the message of the separate Liberal and Nationals strands within the one party.

This is already underway, with O’Sullivan’s bill for a broad-ranging commission of inquiry into banking and other financial institutions, on which he will have final consultations with sympathisers within the Coalition and other parties on Monday.

He then intends to move a motion in the Senate to have it dealt with immediately after the marriage bill is finished there, and debated until it is resolved. Christensen is ready to back it in the lower house.

Treasurer Scott Morrison is still trying to land initiatives to show the government is acting on the banks, short of a royal commission.

The ConversationOne wonders what Peter Dutton, Liberal holder of a marginal Brisbane seat, who last week was open to the government softening its opposition to a royal commission, is thinking right now.

Michelle Grattan, Professorial Fellow, University of Canberra

This article was originally published on The Conversation. Read the original article.

Rise of ‘anti-politics’ produces surprise result in the UK election – and it’s playing a role in Australia, too



File 20170609 20846 159b2e0
Theresa May’s gamble on calling an early election has not paid off.
Reuters/Toby Melville

Brenton Prosser, Australian National University and Gerry Stoker, University of Canberra

A little over a week before the 2017 UK general election, the improbable occurred. A poll indicated that Prime Minister Theresa May could lose the Conservative majority. The shadow of a hung parliament was cast over the UK parliament again. It was a claim credible enough to the markets for the sterling to drop. Most political analysts, however, did not take it seriously.

But these are unconventional times. There is an unlikely president in the White House. No pundit predicted Brexit. And now, a Labour Party led by an “anti-politician” in Jeremy Corbyn has delivered a hung parliament.

While Theresa May will soon be on her way to Buckingham Palace to ask the Queen’s permission to form minority government, the unlikelihood of a stable coalition government means Britons may be heading back to the polls much sooner than they expected.

A win for anti-politics?

“Anti-politics” is often used to describe:

  • a growing distrust of career politicians;

  • hatred of partisan politics; and

  • disaffection with democracy.

Among its causes is complacency in rich Western nations, as well as disinterest in institutions (especially from the young). Many see anti-politics as a tide sweeping away much that was previously taken for granted.

According to leading UK scholars, anti-politics is not a democratic de-alignment as much as the result of political realignment. In other words, it is not that we are turning off democracy – but that we are turning away from political elites and major party politics.

A recent Australian survey found righteous indignation among its citizens. This anger is directed at parties and politicians who are swayed by the quest for power and seem to break promises without impunity.

One of the significant lessons from the 2017 UK poll is that “anti-politics” voters are no longer welded on to any one party. There is growing volatility in the UK electorate. In the 1960s, less than 10% of voters changed their allegiance between elections. In yesterday’s poll it was closer to 40%.

Thanks to anti-politics, gone are the days when voters supported a political party in the way they might support the family football team.

But how then do we explain the strongest combined major party vote for two decades (Conservative 43 / Labour 40)? Does this suggest a return to two-party politics?

No, because one side – Labour – was playing anti-politics.

Corbyn’s success in context

There is no doubt that no-one expected the dramatic growth in the Labour vote. But there are two stories to tell.

First, the support for Corbyn came against economic and political convention. Labour focused on larger cities and university towns, targeting students, service industries and the public sector. It promised to end austerity, nationalise utilities, increase taxes, and invest heavily in public services. It was an anti-political appeal.

Second, the Labour vote was a big enough to hamper the Conservatives, but not much more.

Despite Labour’s celebration over approximately 30 seats, the 2017 result is only eight seats more than when it lost power in 2010. The reality is that Labour is little closer to the 60-plus seats it needs for power than it was last week. What will make this a potentially insurmountable gap is an unacknowledged divide in the UK electorate.

A deeper UK divide

Recently, UK researchers analysed the 2015 UK election results. They found that anti-politics attitudes spread across all voter groups. But what was really challenging for parties was not a traditional split along class lines, but a growing “bifurcation” in the vote of cosmopolitan and provincial England.

Cosmopolitan voters had benefited more from globalisation, were more outward-looking, pluralist and open to the EU. In contrast, those in provincial regions of economic decline were more inward-looking, illiberal, and negative toward immigration.

Perhaps there are no great surprises here. But what is interesting is that this division had real effects that challenged political parties. In other words, these shifts made it harder for larger parties to develop a platform that spans these “two Englands”.

In 2015, this resulted in cosmopolitan votes for Labour and the Greens. It saw provincial support for UKIP and an element of both for the Conservatives.

This suggests that the Conservatives’ 2015 success was due to being more adept at targeting appeals to both cosmopolitan and provisional electorates, while being more pragmatic around taking nationally consistent positions.

What happened in the 2017 general election?

While the Conservatives won 5.5% more of the vote (but lost a dozen seats), Labour won a 7% swing in cosmopolitan areas that had voted Conservative and “Remain”. While participation was up 2.6% overall (up from 66.1% in 2015), it rose by over 5% in seats Labour won.

On the back of record youth enrolment to vote, Labour surged in the youth vote in cosmopolitan areas. Meanwhile, Conservative London cosmopolitan seats changed hands, while Labour won university seats like Sheffield Hallam from the Liberal Democrats.

Yet the challenge for Labour remains. Its wins were cosmopolitan, with little progress in the provincial areas that it needs for a majority in the future.

Meanwhile, the Conservative appeal to provincial England through an emphasis on Brexit and bringing down net migration were successfully targeted at a collapsing UKIP and winning some SNP seats. But it compromised the Tories’ cosmopolitan wins from 2015.

Here lies the challenge for all large party leaders: how do they connect with prevailing moods in both cosmopolitan and provincial areas when they diverge in such opposite directions?

What might this mean for Australia?

It is not unreasonable to suggest Australia may be seeing its own version of the “bifurcation” challenge.

Australian demographer Bernard Salt has already identified a tale of two nations. And as Ken Henry recently observed, the Australian population continues to grow beyond the capacity of existing capital cities and puts pressure on economic performance and infrastructure planning. This can only contribute to “two Australias” that are divided by geography, economic opportunity and even identity.

Meanwhile, some states (hit hard by globalisation) have turned to provincial, protectionist and issue-based politicians. And, as national votes become harder to span, the notion of slim majority as mandate will become even more problematic.

Many argue that former prime minister John Howard’s ability to win traditional Labor voters was at the heart of his sustained electoral success.

The ConversationHowever, the challenge for today’s Australian leaders is more complex than it was during the Howard era. Not only must they manage competing ideologies in their parties and span diverging nations, they must also respond to a volatile electorate that is decidedly “anti-politics”.

Brenton Prosser, Senior Fellow, Australian National University and Gerry Stoker, Fellow and Centenary Professor, Institute for Governance and Policy Analysis, University of Canberra

This article was originally published on The Conversation. Read the original article.

Cricket: The Ashes – Third Test


Not too long ago Australia won the Ashes and are now leading the 5 test series against England 3-0. A fantastic result for Australia, but it was also great that England showed a bit of fight in this match.

Pakistan: Nawaz Sharif Elected


The link below is to an article with the main result of the Pakistan election – Nawaz Sharif has been returned to government.

For more visit:
http://www.guardian.co.uk/world/2013/may/12/pakistan-elects-nawaz-sharif-imran