In the fight against the coronavirus, one key component of the human immune system has hogged the limelight: antibodies.
These Y-shaped proteins have made top news recently because Covid-19 shots don't produce as many of them that work against the heavily mutated Omicron variant compared to past strains -- at least, not without a booster.
Trained by both vaccines and infection, antibodies grab on to the spike protein that studs the surface of the coronavirus, stopping it from penetrating cells and sickening the host.
But while antibodies are rightly celebrated, they're not the only game in town.
In fact, "there's a complex and coordinated response that is really beautiful from an evolutionary standpoint," Harvard immunologist Roger Shapiro explains.
Here are some key points:
'Carpet bombers' of the innate immune system
In the minutes and hours after the virus first comes calling, signaling proteins send out alarms to recruit the tough-but-dim brutes of the "innate" immune system.
First to the scene are "neutrophils," which make up 50 to 70 percent of all white cells and are quick to fight, but also to perish.
Others include hungry "macrophages" that snarf down pathogens and spit out key bits to help train their smarter colleagues, menacingly named "Natural Killer" cells and "dendritic" cells that pass on their intel to more elite fighters.
"It's sort of like carpet bombing the whole area and hopefully you damage the invader as much as possible... at the same time calling into the headquarters to get your SEAL units ready to go," said John Wherry, an immunologist at the University of Pennsylvania.
B and T cells: intelligence officers and trained assassins
If the invaders aren't driven off, the "adaptive" immune system comes into play.
A few days into a first infection, "B cells" wise up to the threat and start pumping out antibodies.
Vaccination also trains B cells -- mainly inside lymph nodes in our armpits, near the site of injection -- to be primed and ready.
Shapiro likened them to intelligence operatives, holding vital information about threats.
The most potent kinds of antibodies, known as "neutralizing," are like chewing gum sticking to the business end of a key, stopping it from unlocking a door.
There are other, less heralded antibodies that aren't as sticky as the neutralizing kind -- but still help grab a hold of the virus, dragging it towards immune cells, or calling for help and escalating the overall response.
B cells' key partners are "T cells," which can be broadly split into "helpers" and "killers."
"Killers are like assassins, and they go and attack the cells that have been infected," said Shapiro -- but these assassins also inflict collateral damage for the sake of the greater good.
The helper T cells "are like generals," added Shapiro, marshaling troops, spurring B cells to up their production and directing their lethal counterparts toward the enemy.
Stopping severe disease
Because of its heavily mutated spike protein, the Omicron variant may more easily slip by neutralizing antibodies conferred by prior infection or vaccination.
The bad news is this makes people more prone to symptomatic infection. But the good news is that T cells aren't nearly as easily fooled.
T cells have a "periscope" into infected cells, where they can look for the constituent parts of the virus during its replication cycle, said Wherry.
They're much better at recognizing tell-tale signs of foes they've encountered before, even if their clever disguises get them past antibodies.
The killer T cells carry out search-and-destroy missions, poking holes in infected cells, bursting them open, and triggering reactions to bring inflammatory proteins known as "cytokines" to the fight.
Depending on the speed of the response, a vaccinated person with a breakthrough infection might get mild, cold-like symptoms, or moderate, flu-like symptoms -- but the chances of severe disease are drastically reduced.
None of this detracts from the case for boosters, which skyrocket the production of all types of antibodies, and also seem to further train B and T cells.
"Omicron is concerning, but the glass is still half-full -- it's not totally going to evade our responses," Wherry said.
ETX Studio
Sat Dec 18 2021
In the fight against the coronavirus, one key component of the human immune system has hogged the limelight: antibodies.
ANALYSIS - What could happen if Trump rejects the US election results
If Trump seems to be losing, the delay could let him claim fraud and undermine confidence in election officials.
Motorcycling - Marquez wins Australian MotoGP after intense battle with Martin
The 31-year-old, third in the championship standings, has now won the Australian MotoGP four times in the premier class.
Prabowo takes up Indonesian presidency, vows to tackle corruption, other issues
Indonesia's Prabowo Subianto on Sunday took over as president of the world's third-largest democracy, vowing to combat internal issues
Nepal's Sherpas deserve more, says teenager who scaled world's 14 tallest peaks
Sherpas are known for climbing skills that make them the backbone of mountain expeditions.
Inside the underground lab in China tasked with solving a physics mystery
China will soon collect neutrino data, aiming to unravel one of particle physics' biggest mysteries.
Millions in Cuba still without power as major outage persists
Millions of Cubans remain without electricity because of a prolonged outage at the main power plants on the island, Anadolu Agency reported.
Surge in Gaza violence increases famine risk, monitor says
About 1.84 million people across the besieged Palestinian enclave are living through high levels of acute food insecurity.
Israel pounds Beirut and Gaza after rockets hit Israel's north
A drone was launched at Prime Minister Benjamin Netanyahu's holiday home.
Elon Musk promises to award $1 mil each day to a signer of his petition
He awarded a $1 million check to an attendee of his event in Pennsylvania aimed at rallying supporters behind Donald Trump.
Former special forces commander Prabowo to take up Indonesian presidency
Indonesia's Prabowo Subianto will take over as president of the world's third-largest democracy after sweeping the country's election with policies like free meals for school children
Father of Malaysian Islamic banking, Abdul Halim Ismail passes away
His dedication and pioneering spirit played an important role in shaping the journey of Bank Islam as well as leaving a lasting impact on the development of Malaysia's Islamic finance industry.
Zayn Malik postpones US tour dates after One Direction bandmate Liam Payne's death
Payne, 31, died on Wednesday after falling from a third-floor hotel room balcony in Buenos Aires, shocking fans of the boy band.
Why voters in a handful of swing states will decide the US presidential election
The contest will almost certainly be decided by just tens of thousands of voters a tiny fraction of the populace in a handful of states.
INSIGHT - Sudan's war risks 'lost generation' of children
A devastating crisis is unfolding in Sudan, where the most vulnerable members of society children are bearing the brunt of the violence.
Who is Prabowo Subianto, incoming president of Indonesia?
A wealthy ex-general with ties to Indonesia's popular outgoing president and its dictatorial past, looks set to be its next leader.
Trump says he would impose tariffs on China if China went into Taiwan
Republican presidential candidate Donald Trump said he would impose additional tariffs on China if China were to "go into Taiwan,"
Iran's supreme leader says Hamas leader's death will not halt 'Axis of Resistance'
The "Axis of Resistance", built up with years of Iranian support, includes Hamas, the Lebanese Hezbollah group, the Houthi movement in Yemen, and various Shi'ite groups in Iraq and Syria.
Putin says Russia willing to seek compromises between Iran and Israel
Russia is ready to help seek compromises between arch-foes Israel and Iran, President Vladimir Putin said on Friday, saying these would be difficult but possible.
What proposals will Russia push at the BRICS summit?
The proposal is also to establish a BRICS reinsurance company to allow uninterrupted shipment of goods and key commodities between members.
Indonesia's free meals plan in the spotlight as Prabowo readies for office
Prabowo calls the programme one of the main drivers of economic growth, eventually set to add an estimated 2.5 million jobs.